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Quantum Volume
Quantum volume is a metric that measures the capabilities and error rates of a quantum computer. It expresses the maximum size of square quantum circuits that can be implemented successfully by the computer. The form of the circuits is independent from the quantum computer architecture, but compiler can transform and optimize it to take advantage of the computer's features. Thus, quantum volumes for different architectures can be compared. The current world record for highest quantum volume as of February 2023 is 32,768 (215), accomplished by Quantinuum's H1 Ion trap quantum computer. Introduction Quantum computers are difficult to compare. Quantum volume is a single number designed to show all around performance. It is a measurement and not a calculation, and takes into account several features of a quantum computer, starting with its number of qubits—other measures used are gate and measurement errors, crosstalk and connectivity. IBM defined its Quantum Volume metric because ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Quantum Computing
Quantum computing is a type of computation whose operations can harness the phenomena of quantum mechanics, such as superposition, interference, and entanglement. Devices that perform quantum computations are known as quantum computers. Though current quantum computers may be too small to outperform usual (classical) computers for practical applications, larger realizations are believed to be capable of solving certain computational problems, such as integer factorization (which underlies RSA encryption), substantially faster than classical computers. The study of quantum computing is a subfield of quantum information science. There are several models of quantum computation with the most widely used being quantum circuits. Other models include the quantum Turing machine, quantum annealing, and adiabatic quantum computation. Most models are based on the quantum bit, or "qubit", which is somewhat analogous to the bit in classical computation. A qubit can be in a 1 or 0 quantum s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Quantum Circuit
In quantum information theory, a quantum circuit is a model for quantum computation, similar to classical circuits, in which a computation is a sequence of quantum gates, measurements, initializations of qubits to known values, and possibly other actions. The minimum set of actions that a circuit needs to be able to perform on the qubits to enable quantum computation is known as DiVincenzo's criteria. Circuits are written such that the horizontal axis is time, starting at the left hand side and ending at the right. Horizontal lines are qubits, doubled lines represent classical bits. The items that are connected by these lines are operations performed on the qubits, such as measurements or gates. These lines define the sequence of events, and are usually not physical cables. The graphical depiction of quantum circuit elements is described using a variant of the Penrose graphical notation. Richard Feynman used an early version of the quantum circuit notation in 1986. Reversible ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Qubit
In quantum computing, a qubit () or quantum bit is a basic unit of quantum information—the quantum version of the classic binary bit physically realized with a two-state device. A qubit is a two-state (or two-level) quantum-mechanical system, one of the simplest quantum systems displaying the peculiarity of quantum mechanics. Examples include the spin of the electron in which the two levels can be taken as spin up and spin down; or the polarization of a single photon in which the two states can be taken to be the vertical polarization and the horizontal polarization. In a classical system, a bit would have to be in one state or the other. However, quantum mechanics allows the qubit to be in a coherent superposition of both states simultaneously, a property that is fundamental to quantum mechanics and quantum computing. Etymology The coining of the term ''qubit'' is attributed to Benjamin Schumacher. In the acknowledgments of his 1995 paper, Schumacher states that the term ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cross-entropy Benchmarking
Cross-entropy benchmarking (also referred to as XEB) is a quantum computer, quantum benchmarking protocol which can be used to demonstrate quantum supremacy. In XEB, a random quantum circuit is executed on a quantum computer multiple times in order to collect a set of k samples in the form of bitstring, bitstrings \. The bitstrings are then used to calculate the cross-entropy benchmark fidelity (F_) via a Computer#Digital_computers, classical computer, given by :F_= 2^ \langle P(x_) \rangle_ - 1 = \frac \left(\sum_^, \langle 0^, C, x_\rangle, ^\right) - 1, where n is the number of qubit, qubits in the circuit and P(x_) is the probability of a bitstring for an ideal quantum circuit C. If F_ = 1, the samples were collected from a noiseless quantum computer. If F_ = 0, then the samples could have been obtained via random guessing. This means that if a quantum computer did generate those samples, then the quantum computer is too noisy and thus has no chance of performing beyon ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
IonQ
IonQ is a quantum computing hardware and software company based in College Park, Maryland. They are developing a general-purpose trapped ion quantum computer and software to generate, optimize, and execute quantum circuits. History IonQ was co-founded by Christopher Monroe and Jungsang Kim, professors at the University of Maryland and Duke University, respectively, in 2015, with the help of Harry Weller and Andrew Schoen, partners at venture firm New Enterprise Associates. The company is an offshoot of the co-founders’ 25 years of academic research in quantum information science. Monroe's quantum computing research began as a Staff Researcher at the National Institute of Standards and Technology (NIST) with Nobel-laureate physicist David Wineland where he led a team using trapped ions to produce the first controllable qubits and the first controllable quantum logic gate, culminating in a proposed architecture for a large-scale trapped ion computer. Kim and Monroe began collab ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Quantum (journal)
''Quantum'' is an online-only, open-access, peer-reviewed scientific journal for quantum science and related fields. The journal was established in 2017. ''Quantum'' is an arXiv overlay journal, meaning the journal's content is hosted on the arXiv. ''Quantum'' is listed in the Directory of Open Access Journals and the Emerging Sources Citation Index, and it is recognized by the European Physical Society as maintaining a high standard of peer review. See also * ''Discrete Analysis ''Discrete Analysis'' is a mathematics journal covering the applications of analysis to discrete structures. ''Discrete Analysis'' is an arXiv overlay journal, meaning the journal's content is hosted on the arXiv. History ''Discrete Analysis' ...'' References External links * Open access journals Physics journals Publications established in 2017 English-language journals Online-only journals {{physics-journal-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Quantum Logic Gate
In quantum computing and specifically the quantum circuit model of computation, a quantum logic gate (or simply quantum gate) is a basic quantum circuit operating on a small number of qubits. They are the building blocks of quantum circuits, like classical logic gates are for conventional digital circuits. Unlike many classical logic gates, quantum logic gates are reversible. It is possible to perform classical computing using only reversible gates. For example, the reversible Toffoli gate can implement all Boolean functions, often at the cost of having to use ancilla bits. The Toffoli gate has a direct quantum equivalent, showing that quantum circuits can perform all operations performed by classical circuits. Quantum gates are unitary operators, and are described as unitary matrices relative to some basis. Usually we use the ''computational basis'', which unless we compare it with something, just means that for a ''d''-level quantum system (such as a qubit, a quantum register ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Toffoli Gate
In logic circuits, the Toffoli gate (also CCNOT gate), invented by Tommaso Toffoli, is a universal reversible logic gate, which means that any classical reversible circuit can be constructed from Toffoli gates. It is also known as the "controlled-controlled-not" gate, which describes its action. It has 3-bit inputs and outputs; if the first two bits are both set to 1, it inverts the third bit, otherwise all bits stay the same. Background An input-consuming logic gate ''L'' is reversible if it meets the following conditions: ''L''(''x'') = ''y'' is a gate where for any output ''y'', there is a unique input ''x''. The gate ''L'' is reversible if there is a gate ''L''′(''y'') = ''x'' which maps ''y'' to ''x''. From common logic gates, NOT is reversible, as can be seen from its truth table below. The common AND gate is not reversible, because the inputs 00, 01 and 10 are all mapped to the output 0. Reversible gates have been studied since the 1960s. The original motivati ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Forbes
''Forbes'' () is an American business magazine owned by Integrated Whale Media Investments and the Forbes family. Published eight times a year, it features articles on finance, industry, investing, and marketing topics. ''Forbes'' also reports on related subjects such as technology, communications, science, politics, and law. It is based in Jersey City, New Jersey. Competitors in the national business magazine category include ''Fortune'' and ''Bloomberg Businessweek''. ''Forbes'' has an international edition in Asia as well as editions produced under license in 27 countries and regions worldwide. The magazine is well known for its lists and rankings, including of the richest Americans (the Forbes 400), of the America's Wealthiest Celebrities, of the world's top companies (the Forbes Global 2000), Forbes list of the World's Most Powerful People, and The World's Billionaires. The motto of ''Forbes'' magazine is "Change the World". Its chair and editor-in-chief is Steve Fo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Noisy Intermediate-scale Quantum Era
The current state of quantum computing is referred to as the noisy intermediate-scale quantum (NISQ) era, characterized by quantum processors containing 50-100 qubits which are not yet advanced enough for fault-tolerance or large enough to achieve quantum supremacy. These processors, which are sensitive to their environment (noisy) and prone to quantum decoherence, are not yet capable of continuous quantum error correction. This intermediate-scale is defined by the quantum volume, which is based on the moderate number of qubits and gate fidelity. The term NISQ was coined by John Preskill in 2018. Algorithms NISQ algorithms are designed for quantum processors in the NISQ era, such as the variational quantum eigensolver (VQE) and quantum approximate optimization algorithm (QAOA), which use NISQ devices but offload some calculations to classical processors. These algorithms have been successful in quantum chemistry and have potential applications in various fields including phy ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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