Lasers were created 60 years ago this year, when three different laser devices were unveiled by independent laboratories in the United States. A few years later, one of these inventors called the unusual light sources a solution seeking a problem. Today, the laser has been applied to countless problems in science, medicine and everyday technologies, with a market of more than US$11 billion per year.
A crucial difference between lasers and traditional sources of light is the temporal coherence of the light beam, or just coherence. The coherence of a beam can be measured by a number C, which takes into account the fact light is both a wave and a particle.
Read more: Explainer: what is wave-particle duality
From even before lasers were created, physicists thought they knew exactly how coherent a laser could be. Now, two new studies (one by myself and colleagues in Australia, the other by a team of American physicists) have shown C can be much greater than was previously thought possible.
The coherence C is roughly the number of photons (particles of light) emitted consecutively into the beam with the same phase (all waving together). For typical lasers, C is very large. Billions of photons are emitted into the beam, all waving together.
This high degree of coherence is what makes lasers suitable for high-precision applications. For example, in many quantum computers, we will need a highly coherent beam of light at a specific frequency to control a large number of qubits over a long period of time. Future quantum computers may need light sources with even greater coherence.
Read more: Explainer: quantum computation and communication technology
Physicists have long thought the maximum possible coherence of a laser was governed by an iron rule known as the Schawlow-Townes limit. It is named after the two American physicists who derived it theoretically in 1958 and went on to win Nobel prizes for their laser research. They stated that the coherence C of the beam cannot be greater than the square of N, the number of energy-excitations inside the laser itself. (These excitations could be photons, or they could be atoms in an excited state, for example.)
Now, however, two theory papers have appeared that overturn the Schawlow-Townes limit by reimagining the laser. Basically, Schawlow and Townes made assumptions about how energy is added to the laser (gain) and how it is released to form the beam (loss).
The assumptions made sense at the time, and still apply to lasers built today, but they are not required by quantum mechanics. With the amazing advances that have occurred in quantum technology in the past decade or so, our imagination need not be limited by standard assumptions.
The first paper, published this week in Nature Physics, is by my group at Griffith University and a collaborator at Macquarie University. We introduced a new model, which differs from a standard laser in both gain and loss processes, for which the coherence C is as big as N to the fourth power.
In a laser containing as many photons as a regular laser, this would allow C to be much bigger than before. Moreover, we show a laser of this kind could in principle be built using the technology of superconducting qubits and circuits which is used in the currently most successful quantum computers.
Read more: Why are scientists so excited about a recently claimed quantum computing milestone?
The second paper, by a team at the University of Pittsburgh, has not yet been published in a peer-reviewed journal but recently appeared on the physics preprint archive. These authors use a somewhat different approach, and end up with a model in which C increases like N to the third power. This group also propose building their laser using superconducting devices.
It is important to note that, in both cases, the laser would not produce a beam of visible light, but rather microwaves. But, as the authors of this second paper note explicitly, this is exactly the type of source required for superconducting quantum computing.
The standard limit is that C is proportional to N , the Pittsburgh group achieved C proportional to N , and our model has C proportional to N . Could some other model achieve an even higher coherence?
No, at least not if the laser beam has the ideal coherence properties we expect from a laser beam. This is another of the results proven in our Nature Physics paper. Coherence proportional to the fourth power of the number of photons is the best that quantum mechanics allows, and we believe it is physically achievable.
An ultimate achievable limit that surpasses what is achievable with standard methods, is known as a Heisenberg limit. This is because it is related to Heisenbergs uncertainty principle.
Read more: Explainer: Heisenbergs Uncertainty Principle
A Heisenberg-limited laser, as we call it, would not be just a revolution in the design and performance of lasers. It also requires a fundamental rethinking of what a laser is: not restricted to the current kinds of devices, but any device which turns inputs with little coherence into an output of very high coherence.
It is the nature of revolutions that it is impossible to tell whether they will succeed when they begin. But if this one does, and standard lasers are supplanted by Heisenberg-limited lasers, at least in some applications, then these two papers will be remembered as the first shots.
Original post:
Reimagining the laser: new ideas from quantum theory could herald a revolution - The Conversation AU
- The Quantum Computer Revolution Is Closer Than You May Think - National Review [Last Updated On: May 3rd, 2017] [Originally Added On: May 3rd, 2017]
- Time Crystals Could be the Key to the First Quantum Computer - TrendinTech [Last Updated On: May 3rd, 2017] [Originally Added On: May 3rd, 2017]
- quantum computing - WIRED UK [Last Updated On: May 3rd, 2017] [Originally Added On: May 3rd, 2017]
- Chinese scientists build world's first quantum computing machine - India Today [Last Updated On: May 3rd, 2017] [Originally Added On: May 3rd, 2017]
- Here's How We Can Achieve Mass-Produced Quantum Computers - ScienceAlert [Last Updated On: June 6th, 2017] [Originally Added On: June 6th, 2017]
- D-Wave partners with U of T to move quantum computing along - Financial Post [Last Updated On: June 6th, 2017] [Originally Added On: June 6th, 2017]
- Team develops first blockchain that can't be hacked by quantum computer - Siliconrepublic.com [Last Updated On: June 6th, 2017] [Originally Added On: June 6th, 2017]
- Telstra just wants a quantum computer to offer as-a-service - ZDNet [Last Updated On: June 6th, 2017] [Originally Added On: June 6th, 2017]
- Research collaborative pursues advanced quantum computing - Phys.Org [Last Updated On: June 6th, 2017] [Originally Added On: June 6th, 2017]
- Quantum Computing Market Forecast 2017-2022 | Market ... [Last Updated On: June 6th, 2017] [Originally Added On: June 6th, 2017]
- Quantum Computing Is Real, and D-Wave Just Open ... - WIRED [Last Updated On: June 7th, 2017] [Originally Added On: June 7th, 2017]
- FinDEVr London: Preparing for the Dark Side of Quantum Computing - GlobeNewswire (press release) [Last Updated On: June 9th, 2017] [Originally Added On: June 9th, 2017]
- Purdue, Microsoft to Collaborate on Quantum Computer - Photonics.com [Last Updated On: June 9th, 2017] [Originally Added On: June 9th, 2017]
- Scientists May Have Found a Way to Combat Quantum Computer Blockchain Hacking - Futurism [Last Updated On: June 9th, 2017] [Originally Added On: June 9th, 2017]
- Microsoft and Purdue work on scalable topological quantum computer - Next Big Future [Last Updated On: June 12th, 2017] [Originally Added On: June 12th, 2017]
- HYPRES Expands Efforts in Quantum Computing with Launch of European Subsidiary SeeQC - Business Wire (press release) [Last Updated On: June 12th, 2017] [Originally Added On: June 12th, 2017]
- From the Abacus to Supercomputers to Quantum Computers - Duke Today [Last Updated On: June 13th, 2017] [Originally Added On: June 13th, 2017]
- Accenture, Biogen, 1QBit Launch Quantum Computing App to ... - HIT Consultant [Last Updated On: June 14th, 2017] [Originally Added On: June 14th, 2017]
- The US and China "Quantum Computing Arms Race" Will Change Long-Held Dynamics in Commerce, Intelligence ... - PR Newswire (press release) [Last Updated On: June 14th, 2017] [Originally Added On: June 14th, 2017]
- Quantum Computing Technologies markets will reach $10.7 billion by 2024 - PR Newswire (press release) [Last Updated On: June 14th, 2017] [Originally Added On: June 14th, 2017]
- A Hybrid of Quantum Computing and Machine Learning Is Spawning New Ventures - IEEE Spectrum [Last Updated On: June 14th, 2017] [Originally Added On: June 14th, 2017]
- KPN CISO details Quantum computing attack dangers - Mobile World Live [Last Updated On: June 16th, 2017] [Originally Added On: June 16th, 2017]
- Get ahead in quantum computing AND attract Goldman Sachs - eFinancialCareers [Last Updated On: June 16th, 2017] [Originally Added On: June 16th, 2017]
- Accenture, 1QBit partner for drug discovery through quantum ... - ZDNet [Last Updated On: June 16th, 2017] [Originally Added On: June 16th, 2017]
- Toward optical quantum computing - MIT News [Last Updated On: June 17th, 2017] [Originally Added On: June 17th, 2017]
- Quantum computing, the machines of tomorrow | The Japan Times - The Japan Times [Last Updated On: June 17th, 2017] [Originally Added On: June 17th, 2017]
- Its time to decide how quantum computing will help your ... [Last Updated On: June 18th, 2017] [Originally Added On: June 18th, 2017]
- Israel Enters Quantum Computer Race, Placing Encryption at Ever-Greater Risk - Sputnik International [Last Updated On: June 20th, 2017] [Originally Added On: June 20th, 2017]
- Prototype device enables photon-photon interactions at room ... - Phys.Org [Last Updated On: June 20th, 2017] [Originally Added On: June 20th, 2017]
- Dow and 1QBit Announce Collaboration Agreement on Quantum Computing - Business Wire (press release) [Last Updated On: June 21st, 2017] [Originally Added On: June 21st, 2017]
- Imperfect crystals may be perfect storage method for quantum computing - Digital Trends [Last Updated On: June 21st, 2017] [Originally Added On: June 21st, 2017]
- Dow Chemical, 1QBit Ink Quantum Computing Development Deal - Zacks.com [Last Updated On: June 22nd, 2017] [Originally Added On: June 22nd, 2017]
- Google on track for quantum computer breakthrough by end of 2017 - New Scientist [Last Updated On: June 22nd, 2017] [Originally Added On: June 22nd, 2017]
- USC to lead project to build super-speedy quantum computers - USC News [Last Updated On: June 24th, 2017] [Originally Added On: June 24th, 2017]
- The Quantum Computer Factory That's Taking on Google and IBM ... - WIRED [Last Updated On: June 24th, 2017] [Originally Added On: June 24th, 2017]
- The weird science of quantum computing, communications and encryption - C4ISR & Networks [Last Updated On: June 27th, 2017] [Originally Added On: June 27th, 2017]
- Multi-coloured photons in 100 dimensions may make quantum ... - Cosmos [Last Updated On: June 30th, 2017] [Originally Added On: June 30th, 2017]
- Global Quantum Computing Market Growth at a CAGR of 35.12 ... - PR Newswire (press release) [Last Updated On: June 30th, 2017] [Originally Added On: June 30th, 2017]
- Qudits: The Real Future of Quantum Computing? - IEEE Spectrum - IEEE Spectrum [Last Updated On: June 30th, 2017] [Originally Added On: June 30th, 2017]
- New method could enable more stable and scalable quantum ... - Phys.Org [Last Updated On: June 30th, 2017] [Originally Added On: June 30th, 2017]
- Quantum computers are about to get real | Science News - Science News Magazine [Last Updated On: June 30th, 2017] [Originally Added On: June 30th, 2017]
- Quantum Computing - Scientific American [Last Updated On: June 30th, 2017] [Originally Added On: June 30th, 2017]
- Australia's ambitious plan to win the quantum race - ZDNet [Last Updated On: July 3rd, 2017] [Originally Added On: July 3rd, 2017]
- How quantum mechanics can change computing - The Conversation - The Conversation US [Last Updated On: August 24th, 2017] [Originally Added On: August 24th, 2017]
- UNSW joins with government and business to keep quantum computing technology in Australia - The Australian Financial Review [Last Updated On: August 24th, 2017] [Originally Added On: August 24th, 2017]
- UNSW launches Australia's first hardware quantum computing company with investments from federal and NSW ... - OpenGov Asia [Last Updated On: August 24th, 2017] [Originally Added On: August 24th, 2017]
- Finns chill out quantum computers with qubit refrigerator to cut out errors - ZDNet [Last Updated On: August 24th, 2017] [Originally Added On: August 24th, 2017]
- Hype and cash are muddying public understanding of quantum ... - The Conversation AU [Last Updated On: August 24th, 2017] [Originally Added On: August 24th, 2017]
- IEEE Approves Standards Project for Quantum Computing ... - insideHPC [Last Updated On: August 24th, 2017] [Originally Added On: August 24th, 2017]
- Silicon Quantum Computing launched to commercialise UNSW ... - ZDNet [Last Updated On: August 24th, 2017] [Originally Added On: August 24th, 2017]
- The Era of Quantum Computing Is Here. Outlook: Cloudy ... [Last Updated On: January 30th, 2018] [Originally Added On: January 30th, 2018]
- The Era of Quantum Computing Is Here. Outlook: Cloudy | WIRED [Last Updated On: February 6th, 2018] [Originally Added On: February 6th, 2018]
- Quantum computing in the NISQ era and beyond [Last Updated On: February 6th, 2018] [Originally Added On: February 6th, 2018]
- What is quantum computing? - Definition from WhatIs.com [Last Updated On: February 6th, 2018] [Originally Added On: February 6th, 2018]
- Quantum computers - WIRED UK [Last Updated On: February 19th, 2018] [Originally Added On: February 19th, 2018]
- Is Quantum Computing an Existential Threat to Blockchain ... [Last Updated On: February 21st, 2018] [Originally Added On: February 21st, 2018]
- What is Quantum Computing? Webopedia Definition [Last Updated On: March 25th, 2018] [Originally Added On: March 25th, 2018]
- Quantum Computing Explained - WIRED UK [Last Updated On: April 15th, 2018] [Originally Added On: April 15th, 2018]
- Quantum computing: A simple introduction - Explain that Stuff [Last Updated On: June 2nd, 2018] [Originally Added On: June 2nd, 2018]
- What are quantum computers and how do they work? WIRED ... [Last Updated On: June 22nd, 2018] [Originally Added On: June 22nd, 2018]
- How Quantum Computers Work [Last Updated On: July 22nd, 2018] [Originally Added On: July 22nd, 2018]
- The reality of quantum computing could be just three years ... [Last Updated On: September 12th, 2018] [Originally Added On: September 12th, 2018]
- The 3 Types of Quantum Computers and Their Applications [Last Updated On: November 24th, 2018] [Originally Added On: November 24th, 2018]
- Quantum Computing - VLAB [Last Updated On: January 27th, 2019] [Originally Added On: January 27th, 2019]
- Quantum Computing | Centre for Quantum Computation and ... [Last Updated On: January 27th, 2019] [Originally Added On: January 27th, 2019]
- Microsofts quantum computing network takes a giant leap ... [Last Updated On: March 7th, 2019] [Originally Added On: March 7th, 2019]
- IBM hits quantum computing milestone, may see 'Quantum ... [Last Updated On: March 7th, 2019] [Originally Added On: March 7th, 2019]
- Quantum technology - Wikipedia [Last Updated On: March 13th, 2019] [Originally Added On: March 13th, 2019]
- Quantum Computing | D-Wave Systems [Last Updated On: April 18th, 2019] [Originally Added On: April 18th, 2019]
- Microsoft will open-source parts of Q#, the programming ... [Last Updated On: May 7th, 2019] [Originally Added On: May 7th, 2019]
- What Is Quantum Computing? The Complete WIRED Guide | WIRED [Last Updated On: May 8th, 2019] [Originally Added On: May 8th, 2019]
- The five pillars of Edge Computing -- and what is Edge computing anyway? - Information Age [Last Updated On: October 1st, 2019] [Originally Added On: October 1st, 2019]
- Moore's Law Is Dying. This Brain-Inspired Analogue Chip Is a Glimpse of What's Next - Singularity Hub [Last Updated On: October 1st, 2019] [Originally Added On: October 1st, 2019]
- Experts Gather at Fermilab for International Workshop on Cryogenic Electronics for Quantum Systems - Quantaneo, the Quantum Computing Source [Last Updated On: October 1st, 2019] [Originally Added On: October 1st, 2019]
- Princeton announces initiative to propel innovations in quantum science and technology - Princeton University [Last Updated On: October 1st, 2019] [Originally Added On: October 1st, 2019]
- Detecting Environmental 'Noise' That Can Damage The Quantum State of Qubits - In Compliance [Last Updated On: October 1st, 2019] [Originally Added On: October 1st, 2019]
- Quantum Computing beginning talks with clients on its quantum asset allocation application - Proactive Investors USA & Canada [Last Updated On: October 1st, 2019] [Originally Added On: October 1st, 2019]
- What is quantum computing? The next era of computational evolution, explained - Digital Trends [Last Updated On: October 1st, 2019] [Originally Added On: October 1st, 2019]
- IT sees the Emergence of Quantum Computing as a Looming Threat to Keeping Valuable Information Confidential - Quantaneo, the Quantum Computing Source [Last Updated On: October 23rd, 2019] [Originally Added On: October 23rd, 2019]
- More wrong answers get quantum computers to find the right one - Futurity: Research News [Last Updated On: October 23rd, 2019] [Originally Added On: October 23rd, 2019]