Quantum computing has come a long way since its theoretical birth in the 1980s, with the works of Paul Benioff, Yuri Manin, Richard Feynman and David Deutsch. We still dont have functional, large-scale, universal quantum computers, but it might not be too much longer before we do.
Currently the domain of large companies such as IBM and Google, and physics research labs in universities, the search is on to find the best approach to building one. Leaving aside the work of Canadian company D-Wave Systems, which uses quantum tunnelling effects to solve problems, the two most successful methods for performing quantum computations are through the use of superconductors and trapped ions.
Superconducting computers make use of a Josephson junction: two superconducting electrodes with a barrier down the middle, which exhibits quantum effects when cooled to near absolute zero. Trapped-ion computers, on the other hand, suspend charged particles in magnetic fields to create their quantum gates and induce the desired effects.
These quantum effects include being able to enter a superposition of states. A silicon computer bit can be on or off (0 or 1), but a quantum bit, or qubit, can be 0, 1 or both at the same time. Its mind-blowing, but it works, and when fed the right algorithm it could achieve in an afternoon what it might take a classical supercomputer a billion years to compute.
Thats pretty revolutionary, and the term quantum supremacy was introduced by Caltechs John Preskill to mark the moment quantum computers will exceed the processing power of conventional silicon. That point comes when we have a processor operating at around the 45-50 qubit mark, and some pretty big names think it might be approaching fast.
Earlier this year, Google announced it was planning to run a 50-qubit computer by the end of 2017, and IBM has plans to hit that mark soon too. Its latest machine, a superconducting model weighing in at 17 qubits, is still in the lab, but a five-qubit machine is running and available to the public, with a 16-qubit computer in beta testing. The IBM Quantum Experience has more than 50,000 users who have executed code more than 300,000 times, publishing their results in 17 scientific publications. Theres even an API and code on GitHub to help you get started.
Something you need to keep in mind is they should be perfect qubits, says Dr Stefan Filipp, a quantum computing scientist at IBMs research facility in Zurich, Switzerland. Thats qubits without any influence from the environment, without any noise properties. Theres a grey zone around how many qubits you need to outperform classical computers, but 50 qubits is the first threshold. What we want to make is a universal quantum computer, and that requires perfect qubits, but were realistic enough to know that you dont find perfect qubits.
(Above: Dr Stefan Filipp, Credit: IBM Research)
Whats needed is some form of error correction. We know now that if we have 100 or 1,000 imperfect qubits, we can distill from them one perfect qubit. says Filipp. So if you want to have 50 perfect qubits, depending on how imperfect the real ones are, we have an overhead of 1,000 or even more qubits.
Its still the case that we need to build a system thats actually capable of outperforming a classical computer. We are quite certain that we can do this, but its not clear whether this will be this year, next year or in five years.
Not everyone sees this model of quantum computer as the best way forward, however. Winfried Hensinger, professor of quantum technologies at the University of Sussex, has published a plan for building a quantum computer today, using existing trapped-ion technology.
Trapped ions are a very attractive candidate [for quantum computing] because they can work at room temperature, he says. To solve really interesting problems, you need millions or billions of qubits, so imagine being able to cool all those quantum bits down to such a low temperature. Were talking 0.01K, or -273C, remember.
The method to implement quantum gates with trapped ions has been to use pairs of laser beams, Hensinger explains. They have to be focused to a precision of one-hundredth of the width of a human hair. That can be easily done if you have only a few ions, but imagine you want to build a quantum computer with millions and billions of qubits. The engineering requires you to have millions and billions of laser beams.
Weve been thinking about this for a long time, and developed an entirely different approach involving applying voltage to a microchip to do exactly the same thing. We can now replace millions and billions of laser beams with voltages. In a way its exactly how a classical computer works the transistors in a microprocessor work the same way. You apply a voltage, and that executes logical operations.
(Above: Prof Winfried Hensinger, Credit: University of Sussex)
Sad as we are to see the back of quite so many lasers, at least the finished computer might be impressively large. A quantum computer, because of the way it operates, cant be very small because its unbelievably complicated to isolate the ions in such a way that the quantum effects arent being destroyed by things around them, and thats where you get headlines about computers the size of football pitches, says Hensinger. The machine will need to be modular, with many smaller processors linked together using another innovation connectivity using electrical fields, a sort of incredibly fast quantum Bluetooth. We could start building it today, but it could still take ten years to build a large machine.
Yet even if such a machine were built, what would we do with it? IBMs Quantum Experience has seen experiments geared toward figuring out what works on a quantum computer and how you write an algorithm for it. In the future, we could see applications in quantum chemistry, as Filipp explains: To describe an electron system, you need two complex numbers. For 100 electrons you need 2100 such numbers, and it would take all the data storage available at the moment to even store these. But a quantum computer can handle it, because you dont have to store this information in a bitstream, but in real physical objects. And these quantum objects are described by quantum mechanics, so they have these numbers already intrinsically in them.
Hensinger has a slightly different view. A quantum computer isnt a fast conventional computer, he says. One interpretation of how it works is it makes use of computations across parallel universes and you can already see how mind-bending that is.
It can solve certain problems in maybe a few hours that even the fastest supercomputer in the world would take billions of years to calculate. At the moment an example is breaking encryption, but for every problem you want to solve, you need to write a new algorithm that makes use of this strange ability to do things in multiple parallel universes. Were not going to take some software, run it on a quantum computer and it will run very fast. Thats a misconception.
Hensinger draws an analogy with the Colossus computer created by Alan Turing and Tommy Flowers to crack Germanys teleprinter codes during World War II. In terms of conventional computers, quantum computers are right now in the 1940s, he tells me. Were very impressed by them, but we dont yet know what they can do.
And whats run on them needs to be tailored to their abilities. There are about 50 people in the world, at most, writing quantum computer algorithms, says Hensinger. The key problems are those a conventional computer could never solve; it would take forever. Its disruptive technology it can change an entire sector of business by adding capability that was previously not available.
This certainly sounds remarkable, but Hensingers huge machines and Filipps absolute-zero cooling systems dont sound very consumer-friendly. Will we all end up owning one? Filipp isnt sure. I think when we have quantum computers that are capable of replacing a laptop, the cooling requirements will be solved, but its not in the near term that quantum computers will replace desktop or laptop computers, he says. Our vision of a quantum computer can do anything a normal computer can do, in principle, but you wouldnt use it for that because its too complicated at the moment.
Quantum computing comes of age – Alphr
- 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
- Hype and cash are muddying public understanding of quantum ... - Phys.Org - 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
- 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