The Quantum Debate

Several players are trying hard to win the quantum race, but it appears that the techniques they employ are different. So, what works best?

By now, we all know that quantum computers work through qubits or quantum bits, and rely on the quirky theories of quantum physics. The two technologies on which most of current quantum computing relies on, are superconductors and anyons. While superconductors are conducting materials that offer zero electrical resistance when kept at a super-cooled state, anyons are quasi-particles with their own peculiarities. These two are the prime methods by which qubits are being mostly derived. However, scientists are still playing around with several other source material and methods to create qubits. These include atoms, photons, ions, and even individual phosphorus atoms embedded in silicon, to name just a few. No one is yet sure what works best – and so far, it’s too early to pick a winner.

The Big Brothers

The big players have their own preferences – Microsoft is focussing on anyons, while IBM, Intel and Google are investing big time on superconductors. But it is mostly the small players – including start-ups like IonQ, QuEra, D-Wave, PsiQuantum and Silicon Quantum Computing – that are exploring a range of other experimental approaches to build their own quantum computers.

Experts consider Google’s superconducting qubits to be the current leader of the pack. Around end-2020, they demonstrated how “Sycamore” – their quantum product – can perform a computation in 3:20 minutes that would take the world’s most powerful conventional supercomputer 10,000 years to execute. Google’s innovation employs loops of superconductor that are constricted at one point by a narrowed-down neck or “pinch’ – technically called a Josephson Junction – that invests the loop with quantum properties similar to an atom. As Travis Humble, director of Oak Ridge National Laboratory’s Quantum Computing Institute, described it as a “very significant” milestone to the press. “We finally had a quantum processor that needed a supercomputer to compare whether we were getting the right answer…. As far as I know, that’s the first time that has ever happened,” he elaborated.

Other biggies like IBM and Intel as well as several start-ups like Rigetti and IQM are trying out superconducting qubits too. However, another school of scientists are sceptical about whether superconducting qubits can actually be harvested at a large enough scale to derive real functional benefits in the long term. No one is still quite sure how to get hundreds of thousands of qubits. Google’s Sycamore uses just 54 qubits. IBM is trying to build a 1 million qubits system. For that, they are also investing in a gigantic cooling unit as superconducting qubits should be maintained at temperatures of around minus 270 Celsius (that is, minus 454 Fahrenheit). The cost-benefits are yet to be analysed because no one knows yet how big a truly useful quantum computer will have to be. You cannot go on building humongous freezers all over the place just to get a superfast computer!

Microsoft’s bet is “topological quantum computing”, that centres on a particle called “non-abelian anyon”. This is not a naturally occurring particle but is created under in very specific derived environments, like when strong magnetic fields are applied to ultrathin sheets of semiconductors. It is very experimental, and nothing can be predicted yet, although the industry is keeping a close watch as the name involved is Microsoft!

The Little Siblings

An alternative that is being proposed is called “ion traps”, where an electron is removed from atoms forming the basis of the qubit. The ion is held in position using magnetic fields. The advantage is that such technique can operate perfectly at room temperatures. Austria-based Alpine Quantum Technologies is betting on ion traps. IonQ, a start-up originating from University of Maryland, is their main competitor in this. Both have achieved over 100 qubits – almost double than Google’s machine – with fewer errors than superconducting qubits. Critics are still not convinced, though, and point out that these systems are practically unusable.

D-Wave Systems has come up with its own approach to quantum computing, although that is much debated. Called “annealing”, this technique doesn’t involve operating quantum logic gates. Instead, it allows thousands of superconducting qubits to interact in loosely defined ways. The company claims that this approach facilitates much more rapid scaling up. Critics say that this is not a general-purpose machine and very few problems can be efficiently solved this way. Yet, this approach is being explored by others, including users at NASA, Volkswagen, Lockheed Martin and Oak Ridge National Laboratory.

Other alternative quantum technologies are also under the anvil. Silicon Quantum Computing of Australia is working on qubits derived from electrons hosted on a single phosphorus atom embedded in a silicon chip. However, the company admits they won’t be ready for practical usage before the 2030s.

Palo Alto-based PsiQuantum is investing on leveraging a photon-based qubit technology to create a fully-fledged quantum processor. The photon-based approach was originally developed at the University of Bristol.

Physics says that the Quantum State is a state of uncertainty. The current scenario in the quantum computing industry looks equally uncertain! There are al kinds of players – big and small – and exciting new thoughts are emerging every day. But no one knows who will win, or if at all anyone will win. Because the way things look, experts predict quantum computers might never fully supplant classical machines; if they emerge at all, they will be integrated into existing supercomputing systems in all probabilities.