Category Archives: Quantum Physics

Many scientific facts can find their analogy in the art of dance. Is science truly objective and neutral, and art subjective? The indeterminacy prevailing in the results of measurements given by quantum mechanics can be seen as an adaptation of information visualised in our classical world.

A quantum measurement result depends on many parameters such as the measuring instrument, the interaction between the system with the environment, the observer and even possibly many other facts, but are almost impossible to explain rationally.

During a measurement, the superposition of states in which the system is found collapses into a classical result dependent on the observer. Before the actual performance, the dancer does not yet know the final result of their sequence: will they fall down or meet the gaze of another person in the middle of their dance? These are answered when the performance is completed, collapsing all choreographic possibilities into one reality.

The association between emotion and the famous Bloch Sphere will now be explored. We can represent the state of a qubit by any point belonging to the surface of a unit sphere, giving us infinite possibilities.

This is how we can perceive a dance; each emotion released by the dancer, or spectator, is established from such a large number of parameters, making it impossible to recreate exactly the same state of emotion at a different moment. It all depends on the sensitivity of each individual, the history and experiences, the dancers intention and the spectators interpretation of each of the distinctive movements.

The dancer-spectator entanglement is so unique that there are states of intricate emotions that can be created. The amount of dancers or spectators can be compared with the amount of entangled particles, the greater the amount, the more complex the performance by both systems.

We can also compare the permanent vibrations of microscopic-scale systems, or even the undulation of waves to the ebb and flow of dance. The Pauli exclusion principle, originating from the electronic configuration of atomic orbitals, reminds us that if we raise one leg in arabesque, then the other leg must necessarily be in the opposite state: it is touching the ground and keeping the balance. If we want to swap legs, then the other leg must return to the ground Except if you can levitate!

While only some links are explored here, both the quantum and ballet worlds are fascinating in their own way.

La Casse, Erasmus French physics student-ballerina

Quantum entanglement is a phenomenon where different systems depend on each other regardless of the distance between them.

One of the functions of cloud-based computing is the invocation of quantum simulators through the cloud providing access to quantum processing.

24 EU member states have committed to working together towards the development of a secure quantum communication infrastructure (EuroQCI).

In March 1935, EPR, Einstein, Podolsky and Rosen, introduced, on the basis of philosophical consideration, the notion of elements of reality.

In the notion of locality, the information is hidden inside each quantum system. This is called the local hidden variables theory.

For more trivia see: http://www.um.edu.mt/think

In London, a dancer and doctor named Merritt realised at the beginning of the pandemic that her only dance partner would be a cobot. Therefore, she created a remarkable and amazing performance with her robot partner. Have a look at this unconventional merger: https://youtu.be/uSOHc3ODLzU

Vortices create arbitrary configurations of polariton liquids and can be produced in bizarre fluids which are controlled by quantum mechanics, completely unlike normal liquids. The simulation results of such a phenomenon have a remarkably aesthetic side, similar to dance during a scenic performance involving make-up, costumes, lighting, etc The phase portraits of a double pendulum demonstrating quantum chaos, particle decay plates, the synthesis images of black holes or Higgs bosons present aesthetic and artistic visions.

https://www.universal-robots.com/blog/dancing-through-the-pandemic-how-a-quantum-physicist-taught-a-cobot-to-dance/?fbclid=IwAR0Km-RXiix7nnSnV9wEhNK6rgnrLNTa4lLDqRFcMxolar-NcN1d_Wp8_50

https://www.eurekalert.org/pub_releases/2012-12/uoc-tdo120412.php

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Link between quantum mechanics and ballet - Times of Malta

According to Einsteins Theory of General Relativity, nothing can escape from the gravity of a black hole once it has passed a point of no return, known as the event horizon, explained Niayesh Afshordi, a physics and astronomy professor at Waterloo in 2020 about echoes in gravitational wave signals that hint that the event horizon of a black hole may be more complicated than scientists currently think based on research reporting the first tentative detection of these echoes, caused by a microscopic quantum fuzz that surrounds newly formed black holes.

Hawking Radiation

This was scientists understanding for a long time until Stephen Hawking used quantum mechanics to predict that quantum particles will slowly leak out of black holes, which we now call Hawking radiation, wrote Afshordi. According to Hawkings 1974 conjecture, if one takes quantum theory into account, black holes should glow slightly with Hawking radiation. According to quantum mechanics, pairs of virtual particles and antiparticles are constantly created and annihilated in normal space. But if a pair of virtual particles or photons is created just outside of the event horizon, one may fall into the black hole while the other escapes. To conserve mass and energy, the escape of a newly created particle or photon must be counteracted by a corresponding decrease in the mass of the black hole. Hence, black holes slowly evaporate due to Hawking radiation. The problem is, no astronomer has ever observed Hawkings mysterious radiation..

Hawking theorized that the universes gravitational behemoths, black holes, were not the dark stars astronomers imagined, but they spontaneously emitted light The problem is, no astronomer has ever observed Hawkings mysterious radiation.

The Echoes

Scientists have been unable to experimentally determine if any matter is escaping black holes until the very recent detection of gravitational waves, continued Afshordi. If the quantum fuzz responsible for Hawking radiation does exist around black holes, gravitational waves could bounce off of it, which would create smaller gravitational wave signals following the main gravitational collision event, similar to repeating echoes.

Afshordi and his coauthor Jahed Abedi from Max-Planck-Institut fr Gravitationsphysik in Germany, reported the first tentative findings of these repeating echoes, providing experimental evidence that black holes may lack truly inescapable event horizons, radically different from what Einsteins theory of relativity predicts.

They used gravitational wave data from the first observation of a neutron star collision, recorded by the LIGO/Virgo gravitational wave detectors.

Echoes Confirm Effects of Quantum Physics and Hawking Radiation

The echoes observed by Afshordi and Abedi match the simulated echoes predicted by models of black holes that account for the effects of quantum mechanics and Hawking radiation.

Our results are still tentative because there is a very small chance that what we see is due to random noise in the detectors, but this chance becomes less likely as we find more examples, said Afshordi. Now that scientists know what were looking for, we can look for more examples, and have a much more robust confirmation of these signals. Such a confirmation would be the first direct probe of the quantum structure of space-time.

In an email to The Daily Galaxy Afshordi wrote: If echoes are real, they certainly come in different flavors for different black hole merger events. It appears that some mergers show clear evidence for them, while most dont. We have a hypothesis that the more unequal mergers have louder echoes, which is roughly consistent with the handful of mergers that show evidence for loud echoes.

What is clear. he concluded his email, is that the search for black hole echoes remains one of the rare windows that we have to realistically probe Planck scale physics. That is why many more theoretical and observational studies of this phenomenon are ongoing.

The study, Echoes from the Abyss: A highly spinning black hole remnant for the binary neutron star merger GW170817, was published in the Journal of Cosmology and Astroparticle Physics in November, and was awarded the first place Buchalter Cosmology Prize this month.

Source: Jahed Abedi et al. Echoes from the abyss: a highly spinning black hole remnant for the binary neutron star merger GW170817, Journal of Cosmology and Astroparticle Physics (2019). DOI: 10.1088/1475-7516/2019/11/010

The Daily Galaxy, Maxwell Moe, astrophysicist, NASA Einstein Fellow, University of Arizona via University of Waterloo

Image credit: CCO Public Domain

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Weird World of Quantum Black Holes May Be Radically Different from What Einstein Predicted and Lack Event H - The Daily Galaxy --Great Discoveries...

A Penn State scientist studying crystal structures has developed a new mathematical formula that may solve a decades-old problem in understanding spacetime, the fabric of the universe proposed in Einsteins theories of relativity.

Relativity tells us space and time can mix to form a single entity called spacetime, which is four-dimensional: three space-axes and one time-axis, said Venkatraman Gopalan, professor of materials science and engineering and physics at Penn State. However, something about the time-axis sticks out like sore thumb.

For calculations to work within relativity, scientists must insert a negative sign on time values that they do not have to place on space values. Physicists have learned to work with the negative values, but it means that spacetime cannot be dealt with using traditional Euclidean geometry and instead must be viewed with the more complex hyperbolic geometry.

Gopalan developed a two-step mathematical approach that allows the differences between space and time to be blurred, removing the negative sign problem and serving as a bridge between the two geometries.

A diagram showing the process of creating renormalized blended spacetime. Penn State scientist Venkatraman Gopalan is studying crystal structures and has developed a new mathematical formula that may solve a decades-old problem in understanding spacetime, the fabric of the universe proposed in Einsteins theories of relativity. Credit: Hari Padmanabhan, Penn State

For more than 100 years, there has been an effort to put space and time on the same footing, Gopalan said. But that has really not happened because of this minus sign. This research removes that problem at least in special relativity. Space and time are truly on the same footing in this work. The paper, published on May 27, 2021, in the journal Acta Crystallographica A, is accompanied by a commentary in which two physicists write that Gopalans approach may hold the key to unifying quantum mechanics and gravity, two foundational fields of physics that are yet to be fully unified.

Gopalans idea of general relativistic spacetime crystals and how to obtain them is both powerful and broad, said Martin Bojowald, professor of physics at Penn State. This research, in part, presents a new approach to a problem in physics that has remained unresolved for decades.

In addition to providing a new approach to relate spacetime to traditional geometry, the research has implications for developing new structures with exotic properties, known as spacetime crystals.

Crystals contain repeating arrangement of atoms, and in recent years scientists have explored the concept of time crystals, in which the state of a material changes and repeats in time as well, like a dance. However, time is disconnected from space in those formulations. The method developed by Gopalan would allow for a new class of spacetime crystals to be explored, where space and time can mix.

These possibilities could usher in an entirely new class of metamaterials with exotic properties otherwise not available in nature, besides understanding the fundamental attributes of a number of dynamical systems, said Avadh Saxena, a physicist at Los Alamos National Laboratory.

Gopalans method involves blending two separate observations of the same event. Blending occurs when two observers exchange time coordinates but keep their own space coordinates. With an additional mathematical step called renormalization, this leads to renormalized blended spacetime.

Lets say I am on the ground and you are flying on the space station, and we both observe an event like a comet fly by, Gopalan said. You make your measurement of when and where you saw it, and I make mine of the same event, and then we compare notes. I then adopt your time measurement as my own, but I retain my original space measurement of the comet. You in turn adopt my time measurement as your own, but retain your own space measurement of the comet. From a mathematical point of view, if we do this blending of our measurements, the annoying minus sign goes away.

References:

Relativistic spacetime crystals by V. Gopalan, 27 May, Acta Crystallographica A.DOI: 10.1107/S2053273321003259

From crystal color symmetry to quantum spacetime by M. Bojowald and A. Saxena, 27 May, Acta Crystallographica A.DOI: 10.1107/S2053273321005234

The National Science Foundation funded this research.

Read more here:

Spacetime Crystals: New Mathematical Formula May Solve Old Problem in Understanding the Fabric of the Universe - SciTechDaily

Next week, UC San Diego will honor the journeys of more than 8,000 graduating students. Each of their stories begins differentlyfrom an international childhood spanning over a dozen countries to discovering a love of learning within an isolated jail cellbut their paths all converged at UC San Diego. Their resilience and accomplishments will be recognized during a series of 10 in-person Commencement ceremonies held June 12-13. Across majors and schools, graduates demonstrate a commitment to their community and a genuine desire to make a difference in the lives of others. Here, the first of a two-part series about the Class of 2021.

Physics doctoral recipient

At 19 years old, Sean Bearden found himself facing an eight-year jail sentence for a violent felony. While isolated in prison, he was drawn to reading for the first time in his life despite a history of indifference to education. When his mother discoveredBeardens change of heart towards education, she began to research distance learning programs and learned ofan associates degree program available through Ohio University. At the time immersed in quantum mechanics, Bearden jumped at the chance to enroll in remote math, science and physics courses.

After being released in mid-2011 and transitioning to work at a collection agency, Bearden aligned on the path he set for himself to achieve a doctoral degree in physics. Though initially somewhat insecure about starting an undergraduate degree at 26 years old, he realized he had cultivated study habits and discipline in prison that his younger peers had not. After completing a bachelors degree, he won a National Science Foundation fellowship and was accepted to UC San Diego as a Sloan Scholar.

The pursuit of a doctorate felt like my only opportunity to overshadow my past, explained Bearden. I was a nontraditional student who made it into one of the top doctoral programs in the country; I could not let the opportunity slip away. I knew a doctorate would change my life.

At UC San Diego, Bearden designed and employed novel, nonlinear dynamical systems, known as digital memcomputing machines, and received the UC Presidents Dissertation Year Fellowship for his research. Since finishing his degree, he is working in data science and quantitative finance and plans to stay active with the UC San Diego community, participating in Grad Talks and mentoring students.

Eleanor Roosevelt College, Global Health

When the COVID-19 pandemic started, UC San Diegos Basic Needs Hub became an even more critical resource to the student population. But the team had to be innovative in serving students safely. As a Basic Needs Assistant, Cieara Simmons was among the first contacts for students reaching out for food, housing and financial support. She explained that her best memories during her time at UC San Diego happened during the two years she served in the role.

Growing up in a low-income household sprouted my awareness of assistance programs and their purpose, explained Simmons. Benefiting from the center as a sophomore encouraged me to apply, so I could also help others and increase awareness about basic needs. Being able to converse with students at the center and learn more about them as individuals continuously motivates me to keep doing the work.

According to Simmons, one of the most effective pandemic pivots at the Hub is the option to order and pick up personal care items. She helped book over 1,000 appointments in the past year for students who could no longer access hygiene essentials. The program offers a wide variety of free products each week, from toothpaste and shampoo to sunscreen and small first aid kits. Hearing students thanks and appreciation for the work we do makes it so worth it! said Simmons.

After graduation, Simmons plans to return to the Bay Area and serve as a resident payee at the Tenderloin Housing Clinic, which works to prevent tenant displacement, expand San Franciscos low-cost housing and provide legal assistance to low-income tenants. After the gap year, her goal is to earn a masters degree in social work and continue to make a difference.

Muir College, Cognitive and Behavioral Neuroscience

Natalia Rossana Menndez has mastered the skill of adapting. She received a global education growing up after living in eight countries and attending 13 schools. As a Mexican international student, Menndez explains that while she was exposed to numerous cultures and people at a very young age, it was difficult leaving friends behind. Amid constant change, she found stability in her family, who prepared her to accept challenges as they come and expect mistakes but keep moving forward with an open heart.

My parents taught me the importance of perspective, she said. Instead of hitting a wall, I was getting over a speedbump. Obstacles in life arent meant to stop you or prevent you from reaching your path;sometimes you just need to slow down to see the bigger picture. I think this gave me a very unique and interesting point of view about life.

A cognitive and behavioral neuroscience major, Menndez is passionate about helping those with neurodegenerative diseases. As part of her honors thesis, she is working with Professor David Kirsh to design environments that positively impact neuropsychological states for patients with Alzheimers disease and dementia. By intentionally adjusting color, temperature, brightness and noise, the goal is to improve cognition and comfort levels.

Menndez has also dedicated her time as a volunteer research assistant at the Veterans Medical Research Foundation at the VA Medical Center. By working with patients who have Alzheimers disease, she has a better understanding of how vast the opportunities are in her chosen field and how much she enjoys working closely with cognitively impaired patients. After graduation she plans to continue her volunteer work and apply for a neuroscience Ph.D. program.

Mechanical Engineering, Warren College

Efran Martinez, pictured in the race car, with members of Triton Racing team after finishing 13th at Formula SAE national competition at Lincoln, Nebraska in 2019.

Each year, a team of UC San Diego engineering students designs, fabricates, and tests an open-wheel race car for the national Formula Society of Automotive Engineers competition. The prospect of gaining real-world experience and working alongside a team of peers sounded exciting to Efran Martinez when he began his sophomore year. After joining the team and exploring different roles, he became chassis lead and oversaw the design, manufacturing and integration of components such as brakes, safety and frame. Martinez became president during his senior year and oversaw the entire project, with special focus on increasing opportunities for new members.

After hearing about Triton Racing and seeing a student-designed performance racecar, I knew it was something I wanted to be a part of, said Martinez, a mechanical engineering major at Warren College. While I had essentially no hands-on engineering experience and very little knowledge about cars at the time, I was very eager to learn and contribute to the project.

In addition to his leadership role in Triton Racing, Martinez served as Associated Students Engineering Senator. As a representative, he increased awareness about engineering student projects and secured external funding resources and sponsorships so that students did not have to contribute their own funds for activities such as traveling to competitions. The goal was to ensure teams had equal access to all hands-on learning experiences, no matter their financial circumstances.

Following graduation, Martinez will begin a rotational program with Rivian, an adventurous electric vehicle company, where he hopes to contribute to vehicle structures and help drive the transition towards sustainable transportation.

Continued here:

Celebrating the Class of 2021 | UC San Diego News - UC San Diego Health

My days have changed drastically. The fight between chaos and control that used to define my life has at last subsided. We have reached a peaceful compromise.

Like others diagnosed with ADHD later in life, I struggled with a host of situations and skills prior to fully understanding my brain and how to work with it, not against it. Without this knowledge, I was left to blame myself for shortcomings, all while my dopamine-deprived brain desperately grasped for anything to alleviate its starved state.

These deficits are debilitating. They elicit much anxiety and can make it impossible to complete any task in an appropriate timeframe.

Consider this innocuous statement: The quiz will start at 2 p.m.

To a neurotypical college student, this statement means that by the time 2 p.m. rolls around, you better clear your schedule for the task. In the meantime, you can carry on with your day as usual.

But the ADHD college student will find it impossible to focus on anything except the quiz all day. It will be the sole event of the day around which everything else revolves. Anything occurring before 2 p.m. will be done on autopilot, lacking appropriate attention, as all available attention is on the upcoming quiz.

[Free Time Assessment Chart for Adults with ADHD]

Until recently, I did not understand why watching a 30-minute lecture was a 2-hour task for me. Why couldnt I watch the lecture while taking notes like my peers? I did not understand why Id start reading a textbook chapter only to remember that I need to wash my bowl of oatmeal, and while rinsing the bowl, Id notice a speck on the counter that would prompt me to clean the whole kitchen, thereby confronting the chips on the counter that would remind me I needtofillmywaterandtheicetrayandwheredidIleavemyphone?

Oh no, my quiz closes soon, and I have a long way to go. Im so disappointed in myself. Why didnt I just do what I needed to?

I hope the previous paragraphs chaos illustrates just a portion of what someone with ADHD experiences. This was how I spent my time every day. Now, with what I know about ADHD, I am finding healthy ways to manage and spend my time.

Even as I type each sentence of this blog post and think of what I most want to illustrate, I realize that I have not stopped to check my phone, to get a snack, or to start another task. I havent even zoned out. A low battery alert flashes on my screen, but I dont want to get my charger because I am so committed to writing.

[Read: 12 Ways to Maintain Focus All Day Long]

This is a mindset and ability Ive desired for a long time and one I was denied all this time by a chemical imbalance. Now, my ideas can flourish as they are meant to. I can dream, initiate, work on, and accomplish my goals.

The time is 8:26 p.m. So far today, I have worked a shift in the ER, exercised at the gym, gone grocery shopping, eaten three meals, tutored, and done some studying. This productivity would not have been possible before my diagnosis. In those times, I would fantasize about all the tasks I had in mind to complete in a day, until inattention, distractions, and chronic exhaustion ruined my ability to focus on a single one.

The curious thing about the ability to pay attention is its mask of simplicity. Paying attention is anything but simple. It depends on a world of complexity. Eye contact, planning, relationships, self-reflection, and so many more aspects that enrich life require you to be in the moment which you cant do without your full attention.

Finally acquiring the ability to deliberately live my life has been the most profound change of my lifetime. Gone are the days of watching the movie, Jacob Munozs Life. Im now the protagonist in charge of how it all unfolds.

Experiencing life in first person is a blessing. Its great to accomplish the big tasks, but Im equally amazed by the little things I can now attempt. My interest in calligraphy has always been inhibited by my lack of sustained attention. Now, I organize my supplies and set up my station for an hour of continuous creativity. I sit down and create a piece of artwork that I can be proud of, instead of restarting 10 times because of a missed detail.

These profound moments create a new picture of my days activities and timeline.

I always thought jumping between tasks was my way of increasing efficiency without losing focus. But this was merely a failed coping strategy. Switching tasks allows for a variation in stimuli, but it compromises thoroughness. Now, I focus on one task at a time and nothing else.

Quantum physics, calculus, and biology are all disciplines I enjoy studying on my own time. (They can come in handy as a neuroscience major.) I can spend hours talking about each subject, possibly side-tracking into other topics as I get distracted. But its the textbook readings, the 30-minute problems, and other related assignments that have been points of contention. My classmates are able to memorize the contents of a chapter as needed for an exam, without truly grasping the material and how its all connected. I struggled with the opposite the science of quantum physics fascinates me, and I understand what there is to understand. But if I were given a 50-question test about the topic based on a reading, I am sure to fail. Thankfully, I am confident in my knowledge and feel confident employing these concepts. While I do not test well, tests do not always gauge knowledge accurately.

Understanding the once-hidden components of myself hasnt all been easy. Finding a medical provider who could see me and answer my questions proved to be a daunting endeavor. Unanswered calls, texts, emails, and voicemails left me feeling unheard and uncared for as my problems mounted. Just when I started to feel defeated, help arrived in the form of a consultation within the hour. That appointment confirmed that ADHD was at fault for the problems I believed to be of my own doing. It marked the start of my journey toward self-discovery and forgiveness. The support from those around me and my faith in Gods will led me to discover myself as I was intended to be created.

My daily life looks different than it used to, and it will undoubtedly change as I continue on my self-discovery path. Im in my last year of college, but I look forward to the next semester of study where I will work on an assignment in one sitting through completion. I look forward to finding peace in my days, knowing I have accomplished what I sought to. I look forward to appreciating every detail of the beautiful world around me. I look forward to and appreciate the now.

SUPPORT ADDITUDEThank you for reading ADDitude. To support our mission of providing ADHD education and support, please consider subscribing. Your readership and support help make our content and outreach possible. Thank you.

Updated on June 4, 2021

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Im No Longer a Spectator to the Unfolding of My Life. - ADDitude

There are limits to how far back we can see: the earliest galaxies, the first stars, and even the ... [+] emission of the leftover glow from the Big Bang when neutral atoms first stably form. However, if it weren't for the quantum mechanical property of enabling a two-photon transition between higher and lower energy spherical states, our Universe would not only look very different, but we wouldn't be able to see as far back in time or through space.

In many ways, our views of the distant Universe are the closest things well ever get to having a time machine. While we cannot travel back through time, we can do the next best thing: view the Universe not as it is today, but rather as it was a significant amount of time ago. Whenever light is emitted from a distant source like a star, galaxy, or quasar it first needs to traverse the vast cosmic distances separating that source from ourselves, the observer, and that takes time.

Even at the speed of light, it can take billions or even over ten billion years for those signals to arrive, meaning that the farther away we see a distant object, the closer back in time towards the Big Bang were looking. The earliest light we can see, however, comes from a time before any stars or galaxies: when the Universes atomic nuclei and electrons combined to form neutral atoms. Yet its only a very specific quirk of quantum physics that allows us to see the Universe as it was so long ago. Without it, the earliest signals wouldnt exist, and wed be unable to look as far back through space and time as we can today. Heres how quantum physics allows us to see so far back in space and time.

The quantum fluctuations that occur during inflation get stretched across the Universe, and when ... [+] inflation ends, they become density fluctuations. This leads, over time, to the large-scale structure in the Universe today, as well as the fluctuations in temperature observed in the CMB. New predictions like these are essential for demonstrating the validity of a proposed fine-tuning mechanism.

To understand where the earliest observable signal in the Universe comes from, we have to go way back in time: to the earliest instants of the Big Bang. Back when the Universe was hot, dense, almost perfectly uniform, and filled with a mix of matter, antimatter, and radiation, it was expanding incredibly rapidly. In these earliest moments, there were regions of the Universe that were slightly denser than average and regions that were slightly less dense than average, but only by ~1 part in 30,000.

If it were up to gravity alone, the overdense regions would grow, attracting more of the surrounding matter than the average or underdense regions, while the underdense regions would give up their matter to its denser surrounding regions. But the Universe isnt governed only by gravity; the other forces of nature play an important role. Radiation, for example particularly in the form of photons is extremely energetic in the early Universe, and its effects on how matter evolves are important in a number of ways.

At early times (left), photons scatter off of electrons and are high-enough in energy to knock any ... [+] atoms back into an ionized state. Once the Universe cools enough, and is devoid of such high-energy photons (right), they cannot interact with the neutral atoms, and instead simply free-stream, since they have the wrong wavelength to excite these atoms to a higher energy level.

First off, matter (and antimatter), if its electrically charged, will readily scatter off of photons. This means that any quantum of radiation, anytime it encounters a charged particle, will interact and exchange energy with it, with encounters being more likely with low-mass charged particles (like electrons) than high-mass ones (like protons or atomic nuclei).

Second off, as matter attempts to gravitationally collapse, the energy density of that region rises above this average. But radiation responds to those higher energy densities by flowing out of those high-density regions into the lower density ones, and this leads to a sort of bounce, where:

and the cycle continues. When we talk about the fluctuations we see in the cosmic microwave background, they follow a particular pattern of wiggles that corresponds to these bounces, or acoustic oscillations, occurring in the plasma of the early Universe.

As our satellites have improved in their capabilities, they've probes smaller scales, more frequency ... [+] bands, and smaller temperature differences in the cosmic microwave background. The temperature imperfections help teach us what the Universe is made of and how it evolved, painting a picture that requires dark matter to make sense.

But theres a third thing happening concurrently with all of these: the Universe is expanding. When the Universe expands, its density drops, since the total number of particles within it stays the same while the volume increases. A second thing, however, happens as well: the wavelength of every photon every quantum of electromagnetic radiation stretches as the Universe expands. Because a photons wavelength determines its energy, with longer wavelengths corresponding to lower energies, the Universe also cools off as it expands.

A Universe that gets less dense and cools from an initially hot and dense state will do a lot more than just gravitate. At high energies, every collision between two quanta will have a chance to spontaneously create particle/antiparticle pairs; as long as theres enough energy available in each collision to create massive particles (and antiparticles) via Einsteins E = mc, theres a chance it will happen.

At early times, this happens copiously, but as the Universe expands and cools, it stops happening, and instead when particle/antiparticle pairs meet, they annihilate away. When the energy drops to low enough values, only a tiny excess of matter will remain.

In the early Universe, the full suite of particles and their antimatter particles were ... [+] extraordinarily abundant, but as they Universe cooled, the majority annihilated away. All the conventional matter we have left over today is from the quarks and leptons, with positive baryon and lepton numbers, that outnumbered their antiquark and antilepton counterparts.

As the Universe continues to expand and cool and as the density and temperature both drop a number of other important transitions happen. In order:

Its only until this final step is complete a step taking over 100,000 years that the Universe becomes transparent to the light present within it. The ionized plasma that existed previously absorbs and re-emits photons continuously, but once neutral atoms form, those photons simply free-stream and redshift with the expanding Universe, creating the cosmic microwave background we observe today.

A Universe where electrons and protons are free and collide with photons transitions to a neutral ... [+] one that's transparent to photons as the Universe expands and cools. Shown here is the ionized plasma (L) before the CMB is emitted, followed by the transition to a neutral Universe (R) thats transparent to photons. The light, once it stops scattering, simply free-streams and redshifts as the Universe expands, eventually winding up in the microwave portion of the spectrum.

That light, on average, comes to us from a time corresponding to ~380,000 years after the Big Bang. This is incredibly short compared to our Universes history of 13.8 billion years, but is very long compared to the earlier steps, which occur over the first fraction-of-a-second to the first few minutes after the Big Bang. Because photons outnumber atoms by more than a billion-to-one, even a tiny number of super-energetic photons can keep the entire Universe ionized. Only when they cool to a specific threshold corresponding to a temperature of about ~3000 K can these neutral atoms finally form.

But theres an immediate problem with that final step, if you think about it.

When electrons bind to atomic nuclei, theyll cascade down the various energy levels in a chain reaction. Eventually, those electrons will make their most energetic transition: to the ground state. The most common transition that occurs is from the second-lowest energy state (called n=2) to the lowest state (n=1), in which case it emits an energetic, Lyman-series photon.

Electron transitions in the hydrogen atom, along with the wavelengths of the resultant photons, ... [+] showcase the effect of binding energy and the relationship between the electron and the proton in quantum physics. Hydrogen's strongest transition is Lyman-alpha (n=2 to n=1), but its second strongest is visible: Balmer-alpha (n=3 to n=2).

Why is this a problem? We needed the Universe to cool below about ~3000 K so that there wouldnt be enough energetic photons to re-excite those ground-state electrons back to an excited state, where theyd be easy to ionize. So we waited and waited and waited, and finally, a few hundred thousand years after the Big Bang, we got there. At that time, electrons bind to nuclei, they cascade down their various energy levels, and finally make a transition down to a ground state.

That energetic, final transition causes the emission of a high-energy, Lyman-series photon. Now, if youve begun to form neutral atoms all over the Universe, you can calculate how far that Lyman-series photon travels before smashing into a neutral atom, and compare that to the amount of redshifting that will occur for that photon. If it redshifts by a great enough amount, its wavelength will lengthen and atoms wont be able to absorb it. (Remember, atoms can only absorb photons of particular frequencies.)

When you do the math, however, you find that the overwhelming majority of photons produced by these transitions to the ground state about 99,999,999 out of every 100,000,000 simply get reabsorbed by another, identical atom, which then can very easily become ionized.

When an electron transitions from a higher-energy state to a lower-energy state, it typically emits ... [+] a single photon of a particular energy. That photon, however, has the right properties to be absorbed by an identical atom in that lower-energy state. If this were to occur exclusively for a hydrogen atom reaching the ground state in the early Universe, it would not be sufficient to explain our cosmic microwave background.

This implies something rather disturbing: we waited all this time for the Universe to become electrically neutral, and then when it does, we calculate that practically every atom that does so will itself be responsible for re-ionizing a different atom of the same type.

You might think that this means we just need to wait for a sufficient amount of time, and then enough of these transitions will occur with a sufficiently long time passing between when those photons are emitted and it encounters another atom. Thats true, but the time it would take for the Universe to become electrically neutral wouldnt be ~380,000 years if this were the way it happened. Instead, it would take more like ~790,000 years for this transition to occur, where the Universe would have dropped all the way down to more like ~1900 K in temperature.

In other words, the simplest way youd attempt to form neutral atoms the way it happens naturally when the ions in our Universe recombine today cannot be the main mechanism for how it occurred in the early Universe.

The lowest energy level (1S) of hydrogen, top left, has a dense electron probability cloud. Higher ... [+] energy levels have similar clouds, but with much more complicated configurations. For the first excited state, there are two independent configurations: the 2S state and the 2P state, which have different energy levels due to a very subtle effect.

So how does it happen, then? You have to remember that the lowest-energy state for an electron in an atom, the n=1 state, is always spherical. You can fit up to two electrons in that state, and so hydrogen the most common element in the Universe always has one electron in the n=1 state when it gets there.

However, the n=2 state can fit up to eight electrons: there are two slots in a spherical state (the s-orbital) and two slots in each of the x, y, and z directions (the p-orbitals).

The problem is that transitions from one s-orbital to another are forbidden, quantum mechanically. Theres no way to emit one photon from an s-orbital and have your electron wind up in a lower energy s-orbital, so the transition we talked about earlier, where you emit a Lyman-series photon, can only occur from the 2p state to the 1s state.

But there is a special, rare process that can occur: a two-photon transition from the 2s state (or the 3s, or 4s, or even the 3d orbital) down to the ground (1s) state. It occurs only about 0.000001% as frequently as the Lyman-series transitions, but each occurrence nets us one new neutral hydrogen atom. This quantum mechanical quirk is the primary method of creating neutral hydrogen atoms in the Universe.

When you transition from an "s" orbital to a lower-energy "s" orbital, you can on rare occasion do ... [+] it through the emission of two photons of equal energy. This two-photon transition occurs even between the 2s (first excited) state and the 1s (ground) state, about one time out of every 100 million transitions, and is the primary mechanism by which the Universe becomes neutral.

If it werent for this rare transition, from higher energy spherical orbitals to lower energy spherical orbitals, our Universe would look incredibly different in detail. We would have different numbers and magnitudes of acoustic peaks in the cosmic microwave background, and hence a different set of seed fluctuations for our Universe to build its large-scale structure out of. The ionization history of our Universe would be different; it would take longer for the first stars to form; and the light from the leftover glow of the Big Bang would only take us back to 790,000 years after the Big Bang, rather than the 380,000 years we get today.

In a very real sense, there are a myriad of ways that our view into the distant Universe to the farthest reaches of deep space where we detect the earliest signals arising after the Big Bang that would be fundamentally less powerful if not for this one quantum mechanical transition. If we want to understand how the Universe came to be the way it is today, even on cosmic scales, its remarkable how subtly dependent the outcomes are on the subatomic rules of quantum physics. Without it, the sights we see looking back across space and time would be far less rich and spectacular.

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How Quantum Physics Allows Us To See Back Through Space And Time - Forbes

Superdeterminism makes sense of the quantum world by suggesting it is not as random as it seems, but critics say it undermines the whole premise of science. Does the idea deserve its terrible reputation?

By Michael Brooks

Pete Reynolds

IVE never worked on anything so unpopular! Sabine Hossenfelder, a theoretical physicist at the Frankfurt Institute for Advanced Studies in Germany, laughs as she says it, but she is clearly frustrated.

The idea she is exploring has to do with the biggest mystery in quantum theory, namely what happens when the fuzzy, undecided quantum realm is distilled into something definite, something we would experience as real. Are the results of this genesis entirely random, as the theory suggests?

Albert Einstein was in no doubt: God, he argued, doesnt play dice with the universe. Hossenfelder is inclined to agree. Now, she and a handful of other physicists are stoking controversy by attempting to revive a non-random, deterministic idea where effects always have a cause. The strangeness of quantum mechanics, they say, only arises because we have been working with a limited view of the quantum world.

The stakes are high. Superdeterminism, as this idea is known, wouldnt only make sense of quantum theory a century after it was conceived. It could also provide the key to uniting quantum theory with relativity to create the final theory of the universe. Hossenfelder and her colleagues arent exactly being cheered on from the sidelines, however. Many theorists are adamant that superdeterminism is the most dangerous idea in physics. Take its implications seriously, they argue, and you undermine the whole edifice of science.

So what is the answer? Does superdeterminism deserve its bad reputation or, in the absence of a better solution, do we have little choice but to give it a chance?

Quantum theory describes the behaviour of matter at

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Is everything predetermined? Why physicists are reviving a taboo idea - New Scientist

Its an exciting time in particle physics. The results of a new experiment out of Fermilab in Illinois involving a subatomic particle wobbling weirdly could lead to new ways of understanding our universe.

To understand why physicists are so excited, consider the ambitious task theyve set for themselves: decoding the fundamental building blocks of everything in the universe. For decades, theyve been trying to do that by building a big, overarching theory known as the standard model.

The standard model is like a glossary, describing all the building blocks of the universe that weve found so far: subatomic particles like electrons, neutrinos, and quarks that make up everything around us, and three of the four fundamental forces (electromagnetic, weak, and strong) that hold things together.

But, as Jessica Esquivel, a particle physicist at Fermilab, tells Vox, scientists suspect this model is incomplete.

One of the big reasons why we know its incomplete is because of gravity. We know it exists because apples fall from trees and Im not floating off my seat, Esquivel says. But they havent yet found a fundamental particle that conveys gravitys force, so its not in the standard model.

Esquivel says the model also doesnt explain two of the biggest mysteries in the universe: dark matter, an elusive substance that holds galaxies together, and dark energy, an even more poorly understood force that is accelerating the universes expansion. And since the overwhelming majority of the universe might be made up of dark matter and dark energy, thats a pretty big oversight.

The problem is, the standard model works really well on its own. It describes the matter and energy were most familiar with, and how it all works together, superbly. Yet, as physicists have tried to expand the model to account for gravity, dark matter, and dark energy, theyve always come up short.

Thats why Esquivel and the many other particle physicists weve spoken to are so excited about the results of a new experiment at Fermilab. It involves muons subatomic particles that are like electrons heavier, less stable cousins. This experiment might, finally, have confirmed a crack in the standard model for particle physicists to explore. Its possible that crack could lead them to find new, fundamental building blocks of nature.

Esquivel worked on the experiment, so we asked her to walk us through it for the Unexplainable podcast. What follows is a transcript of that conversation, edited for clarity and length.

What was this muon experiment?

So at Fermilab, we can create particle beams of muons a very, very intense beam. You can imagine it like a laser beam of particles. And we shoot them into detectors. And then by taking a super, super close measurement of those muons, we can use that as kind of a probe into physics beyond our standard model.

So how, exactly, does this muon experiment point to a hole in the model, or to a new particle to fill that gap?

So the muon g-2 experiment is actually taking a very precise measurement of this thing that we call the precession frequency. And what that means is that we shoot a whole bunch of muons into a very, very precise magnetic field and we watch them dance.

They dance?

Yeah! When muons go into a magnetic field, they precess, or they spin like a spinning top.

One of the really weird quantum-y, sci-fi things that happens is that when you are in a vacuum or an empty space, it actually isnt empty. Its filled with this roiling, bubbling sea of virtual particles that just pop in and out of existence whenever they want, spontaneously. So when we shoot muons into this vacuum, there are not just muons going around our magnet. These virtual particles are popping in and out and changing how the muon wobbles.

Wait, sorry ... what exactly are these virtual particles popping in and out?

So, virtual particles, I ... see them as like ghosts of actual particles. We have photons that kind of pop in and out and theyre just kind of like there, but not really there. I think a really good depiction of this, the weirdness of quantum mechanics, is Ant-Man. Theres this scene where he shrinks down to the quantum realm, and he gets stuck and everything is kind of like wibbly-wobbling and somethings there, but its really not there.

Thats kind of like what virtual particles are. Its just hints of particles that were used to seeing. But theyre not actually there. They just pop in and out and mess with things.

So quantum mechanics says that there are virtual particles, sort of like ghosts of particles we already know about in our standard model, popping in and out of existence. And theyre bumping into muons and making them wobble?

Yes. But again, theoretical physicists know this, and theyve come up with a really good theory of how the muon will change with regards to which particles are popping in and out. So we know specifically how every single one of these particles interacts with each other and within the magnetic field, and they build their theories based on what we already know what is in the standard model.

Got it. So even though there are these virtual ghost particles popping in and out, as long as theyre versions of particles we know, then physicists can predict exactly how the muons are going to wobble. So were the predictions off?

So what we just unveiled is that precise measurement doesnt align with the theoretical predictions of how the muons are supposed to wobble in a magnetic field. It wobbled differently.

And the idea is that you have no idea whats making it do that extra wobble, so it might be something that hasnt been discovered yet? Something outside the standard model?

Yeah, exactly. Its not considered new physics yet because we as physicists give ourselves a very high bar to reach before we say something is potentially new physics. And thats 5 sigma [a measure of the probability that this finding wasnt a statistical error or a random accident.] And right now, were at 4.2 sigma. But its pretty exciting.

So if it clears that bar, would this break the standard model? Because Ive seen that framing in a bunch of headlines.

No, I dont think I would say the standard model is broken. I mean, weve known for a long time that its missing stuff. So its not that whats there doesnt work as its supposed to work.

Its just that were adding more stuff to the standard model, potentially. Just like back in the day when scientists were adding more elements to the periodic table ... even back then, they had spots where they knew an element should go, but they hadnt been able to see it yet. Thats essentially where were at now. We know we have the standard model, but were missing things. So we have holes that were trying to fill.

How exciting does all of this feel?

I think its like a career-defining moment. Its a once-in-a-lifetime. Were chasing new physics and were so close, we can taste it.

What Im studying isnt in any textbook that Ive read or peeked through before, and the fact that the work that Im doing could potentially be in textbooks in the future ... that people can be learning about the dark matter particle that g-2 had a role in finding ... it gives me chills just thinking about it!

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A wobbling muon could unlock mysteries of the universe - Vox.com

A new discovery led by Princeton University researchers could upend our understanding of how electrons behave under extreme conditions due to the laws of quantum physics.

The finding provides experimental evidence that this familiar building block of matter often behaves as if it is made of two particles one particle that gives the electron its negative charge and another that gives it a magnet-like property known as spin.

We think this is the first hard evidence of spin-charge separation, said Nai Phuan Ong, Eugene Higgins Professor of Physics, the senior author on a study published this week in the journal Nature Physics.

The experimental results fulfill a prediction made decades ago to explain one of the most mind-bending states of matter, the quantum spin liquid. In all materials, the spin of an electron can point either up or down. In the familiar magnet, the spins uniformly point in one direction throughout the sample when the temperature drops below a critical temperature.

However, in spin liquid materials, the spins are unable to establish a uniform pattern even when cooled very close to absolute zero. Instead, the spins are constantly changing in a tightly coordinated, entangled choreography. The result is one of the most entangled quantum states ever conceived, a state of great interest to researchers in the nascent field of quantum computing.

To describe this behavior mathematically, Nobel prize-winning Princeton physicist Philip Anderson (1923-2020), who first predicted the existence of spin liquids in 1973, proposed an explanation: in the quantum regime an electron may be regarded as composed of two particles, one bearing the electrons negative charge and the other containing its spin. Anderson called the spin-containing particle a spinon.

In this new study, the team searched for signs of the spinon in a spin liquid composed of ruthenium and chlorine atoms. At temperatures a fraction of a Kelvin above absolute zero (or roughly 452 degrees Fahrenheit), ruthenium chloride crystals enter a spin liquid state in the presence of a high magnetic field.

Physics graduate student Peter Czajka and Tong Gao, a 2020 Ph.D. graduate, connected three highly sensitive thermometers to the crystal as it sat in a bath maintained at temperatures close to absolute zero Kelvin. They then applied the magnetic field and a small amount of heat to one crystal edge to measure its thermal conductivity, a quantity that expresses how well it conducts a heat current. If spinons were present, they should appear as an oscillating pattern in a graph of the thermal conductivity versus magnetic field.

The oscillating signal they were searching for was tiny just a few hundredths of a degree change so the measurements demanded an extraordinarily precise control of the sample temperature as well as careful calibrations of the thermometers in a strong magnetic field.

Researchers at Princeton University conducted experiments on materials known as quantum spin liquids, finding evidence that the electrons in the quantum regime behave as if they are made up of two particles. The 3D color-plot, a composite of many experiments, shows how the thermal conductivity Kxx (vertical axis) varies as a function of the magnetic field B (horizontal axis) and the temperature T (axis into the page). The oscillations provide evidence for spinons.

Graph by Peter Czajka, Princeton University

The team used the purest crystals available, ones grown at the U.S. Department of Energys Oak Ridge National Laboratory under the leadership of David Mandrus, materials science professor at the University of Tennessee-Knoxville, and Stephen Nagler, corporate research fellow in ORNLs Neutron Scattering Division. The ORNL team has extensively studied the quantum spin liquid properties of ruthenium chloride.

In a series of experiments extending over nearly three years, Czajka and Gao detected the temperature oscillations consistent with spinons with increasingly higher resolution, providing evidence that the electron is composed of two particles, consistent with Andersons prediction.

People have been searching for this signature for four decades, Ong said. If this finding and the spinon interpretation are validated, it would significantly advance the field of quantum spin liquids.

From the purely experimental side, Czajka said, it was exciting to see results that in effect break the rules that you learn in elementary physics classes.

Czajka and Gao spent last summer confirming the experiments while under COVID-19 restrictions that required them to wear masks and maintain social distancing.

The experiment was performed in collaboration with Max Hirschberger, a 2017 Ph.D. alumnus now at the University of Tokyo; Arnab Banerjee at Purdue University and ORNL; David Mandrus and Paula Lempen-Kelley at the University of Tennessee-Knoxville and ORNL; and Jiaqiang Yan and Stephen E. Nagler at ORNL. Funding at Princeton was provided by the Gordon and Betty Moore Foundation, the U.S. Department of Energy and the National Science Foundation. The Gordon and Betty Moore Foundation also supported the crystal growth program at the University of Tennessee.

The study, Oscillations of the thermal conductivity in the spin-liquid state of -RuCl3, by Peter Czajka, Tong Gao, Max Hirschberger, Paula Lampen-Kelley, Arnab Banerjee, Jiaqiang Yan, David G. Mandrus, Stephen E. Nagler and N. P. Ong, was published in the journal Nature Physics online on May 13, 2021. DOI: 10.1038/s41567-021-01243-x.

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New evidence for electron's dual nature found in a quantum spin liquid . New experiments conducted at - Princeton University

New quantum materials that promise to propel the communications of the future, an AI-driven search to uncover the fundamental laws of physics, and a project to build biomolecular motors have been selected for funding through the Eric and Wendy Schmidt Transformative Technology Fund.

The three projects, led by faculty teams from across the sciences and engineering, aim to pioneer new discoveries with the potential to transform entire fields of inquiry and propel innovation. The projects were selected following a competitive application process in which proposals were evaluated for their potential to accelerate progress on substantial challenges through strides in the development of knowledge and technological capabilities.

These are profoundly significant projects that have the potential to take both our fundamental knowledge and technical capabilities to new, exciting levels, said Dean for Research Pablo Debenedetti, the Class of 1950 Professor in Engineering and Applied Science and a professor of chemical and biological engineering."Rather than iterate, these proposals aim to make major advances in a discipline, and have the capacity to shift the conversation entirely."

The Eric and Wendy Schmidt Transformative Technology Fund spurs the exploration of ideas and approaches that can profoundly enable progress in science or engineering.Eric Schmidt, the former chief executive officer of Google and former executive chairman of Alphabet Inc., Googles parent company, earned his bachelors degree in electrical engineering from Princeton in 1976 and served as a Princeton trustee from 2004 to 2008. He and his wife, Wendy, a businesswoman and philanthropist, created the fund in 2009. Including this years three awards, the fund has supported 27 research projects at Princeton.

From left: Peter Elmer, senior research physicist, physics; Mariangela Lisanti, associate professor of physics; and Isobel Ojalvo, assistant professor of physics

Photo of Elmer by Luisella Giulicchi; photos of Lisanti and Ojalvo by Richard Soden

Embarking on a quest to explore the fundamental mysteries of the universe, a team of physicists will bring the power of artificial intelligence (AI) to the exploration of the subatomic building blocks of matter.

Despite major strides in understanding the physical laws that govern the universe, many open questions remain, including the nature of dark matter and dark energy, which together make up 95% of the universe. A team led by Senior Research Physicist Peter Elmer, Associate Professor of Physics Mariangela Lisanti and Assistant Professor of Physics Isobel Ojalvo will develop methods for applying AI as a tool for searching for new physical phenomena in experiments conducted at particle accelerators such as CERNs Large Hadron Collider (LHC).

Experiments at the LHC have validated the leading theory of the universes makeup, the Standard Model, by confirming theoretical predictions such as the existence of the Higgs particle. Yet, these findings fail to address unsolved questions inadequately explained by the Standard Model, including dark matter, dark energy and the mass of the neutrino. New theories are needed but how does one conduct a search for new principles of physics when one doesnt know what to look for?

AI can assist in this quest by searching through the massive amount of data resulting from particle collision experiments for novel or unexpected results. The team will develop AI-driven algorithms that search for anomalies in the data that hint at new phenomena. Through the training and deployment of AI software, the team will evaluate particle-collision data to look for new physical laws that may explain the unexplained facets of our universe.

From left: Sanfeng Wu, assistant professor of physics; Leslie Schoop, assistant professor of chemistry; Mansour Shayegan, professor of electrical and computer engineering (ECE); and Loren Pfeiffer, senior research scholar in ECE

Photos (from left) by Richard Soden; Todd Reichart; courtesy department of ECE; and David Kelly Crow

Drawing on recent discoveries in quantum materials, a team from the departments of physics, chemistry, and electrical and computer engineering will build a new site for quantum exploration that features some of the most extreme conditions on Earth including ultra-low temperatures, ultra-low and ultra-high pressures, and strong magnetic fields.

Technologies that utilize quantum properties could unlock new capabilities in computing, communicationsand many other areas. Whereas much research has focused on exotic quantum properties in metals and semi-metals, few studies have looked for quantum behaviors in electrical insulators materials in which electrons cannot move freely primarily due to the lack of methods for observing these properties in insulators. Recent work by teams at Princeton have detected intriguing examples of quantum phases in insulators and semi-conductors, but exploring quantum behaviors in these systems requires specialized conditions and new experimental approaches.

To make transformative discoveries in the emerging area of quantum insulators, a team led by Assistant Professor of Physics Sanfeng Wu, Assistant Professor of Chemistry Leslie Schoop, Professor of Electrical and Computer Engineering Mansour Shayegan, and Senior Research Scholar in Electrical and Computer Engineering Loren Pfeiffer will build an experimental research facility in Princetons Jadwin Hall called Station X.

The station will house equipment with which to create extreme temperatures, pressures, magnetic fields, materials purityand other conditions that enable the researchers to evaluate materials with hidden quantum phases. The team will develop advanced measurement systems that combine electronics and optics to provide an unprecedented platform that can explore the synthesis and measurements of a wide range of quantum materials. This project, combining Princetons expertise in chemistry, engineering and physics, will ensure a leading role for Princeton in the emergence of new areas of quantum science.

From left: Sabine Petry,associate professor of molecular biology; Akanksha Thawani, a 2020 Ph.D. graduate in chemical and biological engineering; and Howard Stone, Donald R. Dixon '69 and Elizabeth W. Dixon Professor of Mechanical and Aerospace Engineering

Inspired by the bodys own biological machinery, a team of molecular biologists and mechanical engineers will design tiny motors and perhaps eventually entire factories dedicated to treating diseases.

The technology for building these molecular robotics draws on recent discoveries at Princeton about the nature of the cells skeleton, which consists of long, thin proteins known as microtubules. Nature is adept at constructing devices with moving microtubules that perform work such as propelling movement of single-celled organisms or dividing chromosomes within cells. One such device, the mitotic spindle, consists of microtubule strands that attach to chromosomes and pull them apart during cell division. Microtubules can exert force on other molecules by pulling or pushing against them, they can separate molecules or propel them together, and they can self-assemble into new structures.

Princeton researchers led by Associate Professor of Molecular Biology Sabine Petry have discovered how spindles form and have uncovered molecular mechanisms by which to control them. Petry will team with Howard Stone, the Donald R. Dixon '69 and Elizabeth W. Dixon Professor of Mechanical and Aerospace Engineering, whose expertise in fluid mechanics will help build miniature channels and chips, in which the microtubule-based machines will be assembled.

The team has laid plans to build several types of microtubule-based nanoscale devices, including bio-actuators, which are capable of performing a task such as moving a particle or molecule from one place to another. By connecting microtubule-based machines via channels, guided by fluid streams into certain directions, the researchers will create nanosized assembly lines and potentially eventually factories. The researchers envision this microtubule-based nanotechnology as opening up an entirely new field of science, making complex manipulations of molecules and other small structures possible at the nanoscale.

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Quantum science, particle physics and nanoscale motors awarded support from Eric and Wendy Schmidt Transformative Tech Fund - Princeton University