After decades of heavy slog with no promise of success, quantum computing is suddenly buzzing with almost feverish excitement and activity. Nearly two years ago, IBM made a quantum computer available to the world: the 5-quantum-bit (qubit) resource they now call (a little awkwardly) the IBM Q experience. That seemed more like a toy for researchers than a way of getting any serious number crunching done. But 70,000 users worldwide have registered for it, and the qubit count in this resource has now quadrupled. In the past few months, IBM and Intel have announced that they have made quantum computers with 50 and 49 qubits, respectively, and Google is thought to have one waiting in the wings. "There is a lot of energy in the community, and the recent progress is immense," said physicist Jens Eisert of the Free University of Berlin.
In quantum computing, it's not just the computers themselves that are hard to build. They also need sophisticated quantum algorithms--specialized software that's tailored to get the best out of the machines. Alán Aspuru-Guzik has gained an impressive reputation in academic circles by developing these kinds of algorithms, and now he's taking them to a wider market. A Harvard University professor (who's moving to the University of Toronto) and a 2010 member of MIT Technology Review's Innovators under 35 list, he is the cofounder of a company called Zapata Computing, which launched today with $5.4 million in announced funding. Zapata's ultimate goal is to be a kind of quantum-algorithm superstore, offering a broad range of ready-made software that companies can use to tap the immense processing power quantum computers promise to deliver.
This month IBM and Google both said they aim to commercialize quantum computers within the next few years (Google specified five), selling access to the exotic machines in a new kind of cloud service. The competitors predict a new era in which computers are immensely more powerful, with dividends including more efficient routing for logistics and mapping companies, new forms of machine learning, better product recommendations, and improved diagnostic tests. But before any of that, the first quantum computer to start paying its way with useful work in the real world looks likely to do so by helping chemists trying to do things like improve batteries or electronics. So far, simulating molecules and reactions is the use case for early, small quantum computers sketched out in most detail by researchers developing the new kind of algorithms needed for such machines. Quantum computers, which represent data using quantum-mechanical effects apparent at tiny scales, should be able to perform computations impossible for any conventional computer.
How many qubits are needed to out-perform conventional computers, how to protect a quantum computer from the effects of decoherence and how to design more than 1000 qubits fault-tolerant large scale quantum computers, these are the three basic questions we want to deal in this article. Qubit technologies, qubit quality, qubit count, qubit connectivity and qubit architectures are the five key areas of quantum computing are discussed. Earlier we have discussed 7 Core Qubit Technologies for Quantum Computing, 7 Key Requirements for Quantum Computing. Spin-orbit Coupling Qubits for Quantum Computing and AI, Quantum Computing Algorithms for Artificial Intelligence, Quantum Computing and Artificial Intelligence, Quantum Computing with Many World Interpretation Scopes and Challenges and Quantum Computer with Superconductivity at Room Temperature. Here, we will focus on practical issues related to designing large-scale quantum computers.
A popular misconception is that the potential--and the limits--of quantum computing must come from hardware. In the digital age, we've gotten used to marking advances in clock speed and memory. Likewise, the 50-qubit quantum machines now coming online from the likes of Intel and IBM have inspired predictions that we are nearing "quantum supremacy"--a nebulous frontier where quantum computers begin to do things beyond the ability of classical machines.