Spin-based quantum computers have the potential to tackle difficult mathematical problems that cannot be solved using ordinary computers, but many problems remain in making these machines scalable. Now, an international group of researchers led by the RIKEN Center for Emergent Matter Science have crafted a new architecture for quantum computing.
By constructing a hybrid device made from two different types of qubit—the fundamental computing element of quantum computers—they have created a device that can be quickly initialized and read out, and that simultaneously maintains high control fidelity.
In an era where conventional computers appear to be reaching a limit, quantum computers—which do calculations using quantum phenomena—have been touted as potential replacements, and they can tackle problems in a very different and potentially much more rapid way. However, it has proven difficult to scale them up to the size required for performing real-world calculations.
In 1998, Daniel Loss, one of the authors of the current study, came up with a proposal, along with David DiVincenzo of IBM, to build a quantum computer by using the spins of electrons embedded in a quantum dot—a small particle that behaves like an atom, but that can be manipulated, so that they are sometimes called “artificial atoms.” In the time since then, Loss and his team have endeavored to build practical devices.
There are a number of barriers to developing practical devices in terms of speed. First, the device must be able to be initialized quickly. Initialization is the process of putting a qubit into a certain state, and if that cannot be done rapidly it slows down the device. Second, it must maintain coherence for a time long enough to make a measurement. Coherence refers to the entanglement between two quantum states, and ultimately this is used to make the measurement, so if qubits become decoherent due to environmental noise, for example, the device becomes worthless. And finally, the ultimate state of the qubit must be able to be quickly read out.
While a number of methods have been proposed for building a quantum computer, the one proposed by Loss and DiVincenzo remains one of the most practically feasible, as it is based on semiconductors, for which a large industry already exists.
For the current study, published in Nature Communications, the team combined two types of quits on a single device. The first, a type of single-spin qubit called a Loss-DiVincenzo qubit, has very high control fidelity—meaning that it is in a clear state, making it ideal for calculations, and has a long decoherence time, so that it will stay in a given state for a relatively long time before losing its signal to the environment.
Unfortunately, the downside to these qubits is that they cannot be quickly initialized into a state or read out. The second type, called a singlet-triplet qubit, is quickly initialized and read out, but it quickly becomes decoherent. For the study, the scientists combined the two types with a type of quantum gate known as a controlled phase gate, which allowed spin states to be entangled between the qubits in a time fast enough to maintain the coherence, allowing the state of the single-spin qubit to be read out by the fast singlet-triplet qubit measurement.
According to Akito Noiri of CEMS, the lead author of the study, “With this study we have demonstrated that different types of quantum dots can be combined on a single device to overcome their respective limitations. This offers important insights that can contribute to the scalability of quantum computers.”
The Latest on: Quantum computing
via Google News
The Latest on: Quantum computing
- Scientists Discover A Brand-New State Of Matter That Could Improve Quantum Computerson August 16, 2019 at 9:30 am
Matter can take many forms, from the familiar solid, liquid, and gas to the more complex states found only by tugging at the limits of physics. Researchers have now discovered a new peculiar state of ...
- Thales helps organizations combat the future security threats of quantum computingon August 16, 2019 at 7:40 am
Login or register now to gain instant access to the rest of this premium content! Thales has announced its collaboration with ISARA Corp. and ID Quantique (IDQ), leading providers of complementary ...
- New Report Forecasts $780 Million Quantum Computing Market in 2025 and Profiles 42 Leading Quantum Computing Organizationson August 15, 2019 at 11:28 am
CROZET, Va., Aug 15, 2019 (GLOBE NEWSWIRE via COMTEX) -- According to Quantum Computing Strategies: 2019 https://www.insidequantumtechnology.com/product/quantum-computing-strategies-2019/, a new ...
- Newfound superconductor material could be the 'silicon of quantum computers'on August 15, 2019 at 11:04 am
A potentially useful material for building quantum computers has been unearthed at the National Institute of Standards and Technology (NIST), whose scientists have found a superconductor that ...
- Investing in quantum computingon August 15, 2019 at 7:57 am
Quantum computing has promised much, and absorbed enormous resources, without delivering a great deal in practical terms yet. However, the rationale for investing in research remains impeccable. In ...
- Quantum system virtually cooled to half of its actual temperatureon August 15, 2019 at 7:03 am
Due to their quantum properties, quantum simulators can perform certain tasks like this that are out of the reach of classical computers, which cannot leverage quantum entanglement and superposition.
- IBM Q Wants You To Try Out Its Online Quantum Computer (Radio)on August 14, 2019 at 10:03 am
Bob Sutor, Vice President, IBM Q Strategy & Ecosystem, on building public and commercial quantum computing systems for business and science applications. Hosted by Lisa Abramowicz and Paul Sweeney.
- Airbus Looks For A Quantum LEAP In Computing Poweron August 13, 2019 at 11:23 pm
Once thought of as impossible due to its complexity, quantum computing could be a game-changing technology across industries—from science to medicine. In the aerospace industry, quantum computing is ...
- The Basics of Quantum Computing—A Tutorialon August 13, 2019 at 1:11 pm
In classic computing, uncertainty is unacceptable. With quantum computers, however, it’s an asset. Quantum computers have an innate ability to learn about the world, dealing in probability, as they ...
- The Quantum Computing Party Hasn’t Even Started Yeton August 12, 2019 at 3:40 pm
If you pay even a little attention to technology news, you've undoubtedly heard about the amazing potential of quantum computers, which exploit the unusual physics of the smallest particles in the ...
via Bing News