Just occasionally, Alán Aspuru-Guzik has a movie-star moment, when fans half his age will stop him in the street. "They say, 'Hey, we know who you are'," he laughs. "Then they tell me that they also have a quantum start-up, and would love to talk to me about it." "I don't usually have time to talk, but I'm always happy to give them some tips." That affable approach is not uncommon in the quantum-computing community, says Aspuru-Guzik, who is a computer scientist at the University of Toronto, Canada, and co-founder of quantum-computing company Zapata Computing in Cambridge, Massachusetts.
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.
Quantum computing gets a boost as IBM develops new algorithms, but how will it be beneficial to different industries? IBM scientists have developed new algorithms to help improve the knowledge of complex chemistry and quantum computing. Using IBM Q, the tech team successfully applied an efficient algorithm in relation to the number of quantum operations required for stimulation using a six qubits of a seven-qubit quantum processor to address the molecular structure problem for beryllium hydride which is to date the largest molecule simulated on a quantum computer. As a result of the breakthrough, it could result in effective practical applications across various sectors such as medicine to help develop personalised drugs, material engineering and energy to discover better sustainable energy sources. "Exact predictions will result in molecular design that does not need calibration with experiment.
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.
One of the primary challenges for the realization of near-term quantum computers has to do with their most basic constituent: the qubit. Qubits can interact with anything in close proximity that carries energy close to their own--stray photons (i.e., unwanted electromagnetic fields), phonons (mechanical oscillations of the quantum device), or quantum defects (irregularities in the substrate of the chip formed during manufacturing)--which can unpredictably change the state of the qubits themselves. Further complicating matters, there are numerous challenges posed by the tools used to control qubits. Manipulating and reading out qubits is performed via classical controls: analog signals in the form of electromagnetic fields coupled to a physical substrate in which the qubit is embedded, e.g., superconducting circuits. Imperfections in these control electronics (giving rise to white noise), interference from external sources of radiation, and fluctuations in digital-to-analog converters, introduce even more stochastic errors that degrade the performance of quantum circuits.