An ion trap used for quantum computing research in the Quantum Control Laboratory at the University of Sydney. Michael Biercuk, Author provided Special piping and wiring supports quantum research in the Sydney Nanoscience Hub. Credit: AINST, Author provided
It’s no surprise that quantum computing has become a media obsession. A functional and useful quantum computer would represent one of the century’s most profound technical achievements.
For researchers like me, the excitement is welcome, but some claims appearing in popular outlets can be baffling.
A recent infusion of cash and attention from the tech giants has woken the interest of analysts, who are now eager to proclaim a breakthrough moment in the development of this extraordinary technology.
Quantum computing is described as “just around the corner”, simply awaiting the engineering prowess and entrepreneurial spirit of the tech sector to realise its full potential.
What’s the truth? Are we really just a few years away from having quantum computers that can break all online security systems? Now that the technology giants are engaged, do we sit back and wait for them to deliver? Is it now all “just engineering”?
Why do we care so much about quantum computing?
Quantum computers are machines that use the rules of quantum physics in other words, the physics of very small things to encode and process information in new ways.
They exploit the unusual physics we find on these tiny scales, physics that defies our daily experience, in order to solve problems that are exceptionally challenging for “classical” computers. Don’t just think of quantum computers as faster versions of today’s computers think of them as computers that function in a totally new way. The two are as different as an abacus and a PC.
They can (in principle) solve hard, high-impact questions in fields such as codebreaking, search, chemistry and physics.
Chief among these is “factoring”: finding the two prime numbers, divisible only by one and themselves, which when multiplied together reach a target number. For instance, the prime factors of 15 are 3 and 5.
As simple as it looks, when the number to be factored becomes large, say 1,000 digits long, the problem is effectively impossible for a classical computer. The fact that this problem is so hard for any conventional computer is how we secure most internet communications, such as through public-key encryption.
Some quantum computers are known to perform factoring exponentially faster than any classical supercomputer. But competing with a supercomputer will still require a pretty sizeable quantum computer.
Money changes everything
Quantum computing began as a unique discipline in the late 1990s when the US government, aware of the newly discovered potential of these machines for codebreaking, began investing in university research
The field drew together teams from all over the world, including Australia, where we now have two Centres of Excellence in quantum technology (the author is part of of the Centre of Excellence for Engineered Quantum Systems).
But the academic focus is now shifting, in part, to industry.
IBM has long had a basic research program in the field. It was recently joined by Google, who invested in a University of California team, and Microsoft, which has partnered with academics globally, including the University of Sydney.
Seemingly smelling blood in the water, Silicon Valley venture capitalists also recently began investing in new startups working to build quantum computers.
The media has mistakenly seen the entry of commercial players as the genesis of recent technological acceleration, rather than a response to these advances.
So now we find a variety of competing claims about the state of the art in the field, where the field is going, and who will get to the end goal a large-scale quantum computer first.
The state of the art in the strangest of technologies
Conventional computer microprocessors can have more than one billion fundamental logic elements, known as transistors. In quantum systems, the fundamental quantum logic units are known as qubits, and for now, they mostly number in the range of a dozen.
Such devices are exceptionally exciting to researchers and represent huge progress, but they are little more than toys from a practical perspective. They are not near what’s required for factoring or any other application they’re too small and suffer too many errors, despite what the frantic headlines may promise.
For instance, it’s not even easy to answer the question of which system has the best qubits right now.
Consider the two dominant technologies. Teams using trapped ions have qubits that are resistant to errors, but relatively slow. Teams using superconducting qubits (including IBM and Google) have relatively error-prone qubits that are much faster, and may be easier to replicate in the near term.
Which is better? There’s no straightforward answer. A quantum computer with many qubits that suffer from lots of errors is not necessarily more useful than a very small machine with very stable qubits.
Because quantum computers can also take different forms (general purpose versus tailored to one application), we can’t even reach agreement on which system currently has the greatest set of capabilities.
Similarly, there’s now seemingly endless competition over simplified metrics such as the number of qubits. Five, 16, soon 49! The question of whether a quantum computer is useful is defined by much more than this.
Where to from here?
There’s been a media focus lately on achieving “quantum supremacy”. This is the point where a quantum computer outperforms its best classical counterpart, and reaching this would absolutely mark an important conceptual advance in quantum computing.
But don’t confuse “quantum supremacy” with “utility”.
Some quantum computer researchers are seeking to devise slightly arcane problems that might allow quantum supremacy to be reached with, say, 50-100 qubits numbers reachable within the next several years.
Achieving quantum supremacy does not mean either that those machines will be useful, or that the path to large-scale machines will become clear.
Moreover, we still need to figure out how to deal with errors. Classical computers rarely suffer hardware faults the “blue screen of death” generally comes from software bugs, rather than hardware failures. The likelihood of hardware failure is usually less than something like one in a billion-quadrillion, or 10-24 in scientific notation.
The best quantum computer hardware, on the other hand, typically achieves only about one in 10,000, or 10-4. That’s 20 orders of magnitude worse.
Is it all just engineering?
We’re seeing a slow creep up in the number of qubits in the most advanced systems, and clever scientists are thinking about problems that might be usefully addressed with small quantum computers containing just a few hundred qubits.
But we still face many fundamental questions about how to build, operate or even validate the performance of the large-scale systems we sometimes hear are just around the corner.
As an example, if we built a fully “error-corrected” quantum computer at the scale of the millions of qubits required for useful factoring, as far as we can tell, it would represent a totally new state of matter. That’s pretty fundamental.
At this stage, there’s no clear path to the millions of error-corrected qubits we believe are required to build a useful factoring machine. Current global efforts (in which this author is a participant) are seeking to build just one error-corrected qubit to be delivered about five years from now.
At the end of the day, none of the teams mentioned above are likely to build a useful quantum computer in 2017 or 2018. But that shouldn’t cause concern when there are so many exciting questions to answer along the way.
Explore further: Developing quantum algorithms for optimization problems
This article was originally published on The Conversation. Read the original article.
- How Quantum Computers Work - May 3rd, 2018
- This is what a 50-qubit quantum computer looks like - January 15th, 2018
- Inside Microsofts quantum computing world | InfoWorld - January 1st, 2018
- Microsoft Takes Path Less Traveled to Build a Quantum ... - December 13th, 2017
- Researchers create new type of quantum computer | Harvard Gazette - December 12th, 2017
- Microsoft releases quantum computing development kit preview ... - December 12th, 2017
- Intel moves towards production quantum computing with new 17 ... - October 11th, 2017
- Quantum computer a possibility in 10 years - News.com.au - NEWS.com.au - September 7th, 2017
- Scientists Propose a New Kind of Quantum Computer, But What ... - Gizmodo - September 7th, 2017
- Quantum detectives in the hunt for the world's first quantum computer - Phys.Org - September 7th, 2017
- Scientists Just Found A Use For The Hashtag In Quantum Computing - Gizmodo Australia - September 4th, 2017
- The Future of AI: From Quantum Computing to the Internet of Things - Outer Places - September 4th, 2017
- We're About to Cross The 'Quantum Supremacy' Limit in Computing - ScienceAlert - September 2nd, 2017
- Explaining the Most Recent Record for Quantum Computing: A 51-Qubit Quantum Computer Array - All About Circuits - September 2nd, 2017
- USRA Upgrades D-Wave Quantum Computer to 2000 Qubits - insideHPC - September 1st, 2017
- Quantum encrypted box hints at unhackable communication - Wired.co.uk - September 1st, 2017
- Quantum Computer Programming: What You Need to Learn to Get ... - TrendinTech - September 1st, 2017
- Google's John Martinis Believes Quantum Computing Threat to Be Long Way Off - Bitcoin News (press release) - August 31st, 2017
- Australian quantum computing outfit goes commercial - Networks Asia - August 31st, 2017
- Elusive Majorana Particle Takes Major Step Towards Quantum Computing - IEEE Spectrum - August 29th, 2017
- Australia gets quantum computing company - ACS (registration) - August 28th, 2017
- Quantum Computing and Financial Trading - LeapRate - August 28th, 2017
- Russians Lead the Quantum Computer Race With 51-Qubit Machine - Edgy Labs (blog) - August 28th, 2017
- Bitcoin vs. The NSAs Quantum Computer Bitcoin Not Bombs - August 26th, 2017
- qBitcoin: A Way of Making Bitcoin Quantum-Computer Proof? - IEEE Spectrum - August 26th, 2017
- Silicon Quantum Computing launched to commercialise UNSW ... - ZDNet - August 23rd, 2017
- IEEE Approves Standards Project for Quantum Computing ... - Business Wire (press release) - August 23rd, 2017
- Introducing Australia's first quantum computing hardware company - CIO Australia - August 23rd, 2017
- What is quantum computer? - Definition from WhatIs.com - August 22nd, 2017
- Hype and cash are muddying public understanding of quantum computing - The Conversation AU - August 22nd, 2017
- Finns chill out quantum computers with qubit refrigerator to cut out errors - ZDNet - August 22nd, 2017
- UNSW joins with government and business to keep quantum computing technology in Australia - The Australian Financial Review - August 22nd, 2017
- 'Tools of DESTRUCTION' Quantum computers WILL wreak havoc ... - Express.co.uk - August 19th, 2017
- Quantum computing comes of age - Alphr - August 14th, 2017
- No, Quantum Teleportation Won't Let Us Send Instant Messages to Alpha Centauri - Air & Space Magazine - August 12th, 2017
- Google on track for quantum computer breakthrough by end of ... - August 11th, 2017
- Closing In On Quantum Computing | WIRED - August 11th, 2017
- World's Leading Physicist Says Quantum Computers Are Tools of Destruction, Not Creation - Futurism - August 10th, 2017
- Will you be able to trust a quantum computer? - Digital Journal - August 9th, 2017
- New Methods of Controlling Electrons Could be Major in Quantum Computing - TrendinTech - August 5th, 2017
- Exactly what could quantum computers do? - Electronics Weekly - August 4th, 2017
- What is quantum computing and why does the future of Earth depend on it? - Alphr - August 2nd, 2017
- The Age of Quantum Computers is upon us! - Gizbot - August 2nd, 2017
- Ultracold molecules hold promise for quantum computing | MIT News - MIT News - August 1st, 2017
- Clarifiying complex chemical processes with quantum computers - Phys.Org - August 1st, 2017
- When Will Quantum Computers Be Consumer Products? - Futurism - August 1st, 2017
- Quantum Computers Just Moved a Step Closer to Reality - NBCNews.com - August 1st, 2017
- A New Breakthrough in Quantum Computing is Set to Transform Our ... - Futurism - August 1st, 2017
- Quantum computers compete for supremacy - Salon - July 10th, 2017
- Quantum Computers Compete for "Supremacy" - Scientific American - July 5th, 2017
- Less is more for Canadian quantum computing researchers - ITworld - July 4th, 2017
- New method could enable more stable and scalable quantum ... - Phys.Org - July 4th, 2017
- Volkswagen buys D-Wave quantum computers which sell for $15 million each - Robotics and Automation News (press release) (registration) - July 2nd, 2017
- 6 Things Quantum Computers Will Be Incredibly Useful For - Singularity Hub - July 1st, 2017
- Quantum Machine Learning Computer Hybrids at the Center of New Start-Ups - TrendinTech - June 20th, 2017
- Israel Enters Quantum Computer Race, Placing Encryption at Ever-Greater Risk - Sputnik International - June 20th, 2017
- Prototype device enables photon-photon interactions at room ... - Phys.Org - June 20th, 2017
- The Quantum Computer Factory That's Taking on Google and IBM - WIRED - June 20th, 2017
- Toward optical quantum computing - MIT News - June 17th, 2017
- Get ahead in quantum computing AND attract Goldman Sachs - eFinancialCareers - June 16th, 2017
- KPN CISO details Quantum computing attack dangers - Mobile World Live - June 16th, 2017
- Quantum Computing Technologies markets will reach $10.7 billion by 2024 - PR Newswire (press release) - June 14th, 2017
- From the Abacus to Supercomputers to Quantum Computers - Duke Today - June 13th, 2017
- Quantum Computers Will Analyze Every Financial Model at Once - Singularity Hub - June 13th, 2017
- Are Enterprises Ready to Take a Quantum Leap? - IT Business Edge - June 13th, 2017
- Scientists May Have Found a Way to Combat Quantum Computer Blockchain Hacking - Futurism - June 13th, 2017
- Microsoft and Purdue work on scalable topological quantum computer - Next Big Future - June 13th, 2017
- Doped Diamonds Push Practical Quantum Computing Closer to Reality - Motherboard - June 3rd, 2017
- Team develops first blockchain that can't be hacked by quantum computer - Siliconrepublic.com - June 3rd, 2017
- D-Wave partners with U of T to move quantum computing along - Financial Post - June 2nd, 2017
- Telstra just wants a quantum computer to offer as-a-service - ZDNet - June 1st, 2017
- Microsoft, Purdue Tackle Topological Quantum Computer - HPCwire - HPCwire (blog) - June 1st, 2017
- MIT Just Unveiled A Technique to Mass Produce Quantum Computers - Futurism - June 1st, 2017
- Here's How We Can Achieve Mass-Produced Quantum Computers - ScienceAlert - June 1st, 2017
- Research collaborative pursues advanced quantum computing - Phys.Org - June 1st, 2017
- AI and Quantum Computers Are Our Best Weapons Against Cyber Criminals - Futurism - June 1st, 2017
- Scientists claim to have invented the world's first quantum-proof ... - ScienceAlert - June 1st, 2017
- Google Plans to Demonstrate the Supremacy of Quantum ... - IEEE Spectrum - May 25th, 2017
- Top 5: Things to know about quantum computers - TechRepublic - May 25th, 2017
- Is the US falling behind in the race for quantum computing? - AroundtheO - May 25th, 2017