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A quantum computer is a computer that exploits quantum mechanical phenomena. On small scales, physical matter exhibits properties of both particles and waves, and quantum computing leverages this behavior using specialized hardware. Classical physics cannot explain the operation of these quantum devices, and a scalable quantum computer could perform some calculations exponentially faster than any modern "classical" computer. In particular, a large-scale quantum computer could break widely used encryption schemes and aid physicists in performing physical simulations; however, the current state of the art is largely experimental and impractical, with several obstacles to useful applications.
This is a timeline of quantum computing.
In logic circuits, the Toffoli gate, also known as the CCNOT gate (“controlled-controlled-not”), invented by Tommaso Toffoli, is a CNOT gate with two control qubits and one target qubit. That is, the target qubit will be inverted if the first and second qubits are both 1. It is a universal reversible logic gate, which means that any classical reversible circuit can be constructed from Toffoli gates. Formally, we describe the Toffoli gate with the following truth table and matrix:
A Rydberg atom is an excited atom with one or more electrons that have a very high principal quantum number, n. The higher the value of n, the farther the electron is from the nucleus, on average. Rydberg atoms have a number of peculiar properties including an exaggerated response to electric and magnetic fields, long decay periods and electron wavefunctions that approximate, under some conditions, classical orbits of electrons about the nuclei. The core electrons shield the outer electron from the electric field of the nucleus such that, from a distance, the electric potential looks identical to that experienced by the electron in a hydrogen atom.
Superconducting quantum computing is a branch of solid state quantum computing that implements superconducting electronic circuits using superconducting qubits as artificial atoms, or quantum dots. For superconducting qubits, the two logic states are the ground state and the excited state, denoted respectively. Research in superconducting quantum computing is conducted by companies such as Google, IBM, IMEC, BBN Technologies, Rigetti, and Intel. Many recently developed QPUs use superconducting architecture.
Quantum networks form an important element of quantum computing and quantum communication systems. Quantum networks facilitate the transmission of information in the form of quantum bits, also called qubits, between physically separated quantum processors. A quantum processor is a machine able to perform quantum circuits on a certain number of qubits. Quantum networks work in a similar way to classical networks. The main difference is that quantum networking, like quantum computing, is better at solving certain problems, such as modeling quantum systems.
In condensed matter physics, an ultracold atom is an atom with a temperature near absolute zero. At such temperatures, an atom's quantum-mechanical properties become important.
D-Wave Quantum Systems Inc. is a Canadian quantum computing company, based in Burnaby, British Columbia. D-Wave claims to be the world's first company to sell computers that exploit quantum effects in their operation. D-Wave's early customers include Lockheed Martin, the University of Southern California, Google/NASA, and Los Alamos National Lab.
The toric code is a topological quantum error correcting code, and an example of a stabilizer code, defined on a two-dimensional spin lattice. It is the simplest and most well studied of the quantum double models. It is also the simplest example of topological order—Z2 topological order (first studied in the context of Z2 spin liquid in 1991). The toric code can also be considered to be a Z2 lattice gauge theory in a particular limit. It was introduced by Alexei Kitaev.
In quantum mechanics, quantum scarring is a phenomenon where the eigenstates of a classically chaotic quantum system have enhanced probability density around the paths of unstable classical periodic orbits. The instability of the periodic orbit is a decisive point that differentiates quantum scars from the more trivial observation that the probability density is enhanced in the neighborhood of stable periodic orbits. The latter can be understood as a purely classical phenomenon, a manifestation of the Bohr correspondence principle, whereas in the former, quantum interference is essential. As such, scarring is both a visual example of quantum-classical correspondence, and simultaneously an example of a (local) quantum suppression of chaos.
Quantum simulators permit the study of a quantum system in a programmable fashion. In this instance, simulators are special purpose devices designed to provide insight about specific physics problems. Quantum simulators may be contrasted with generally programmable "digital" quantum computers, which would be capable of solving a wider class of quantum problems.
Mikhail Lukin ; born 10 October 1971) is a Russian theoretical and experimental physicist and a professor at Harvard University. He was elected a member of the National Academy of Sciences in 2018.
Cloud-based quantum computing is the invocation of quantum emulators, simulators or processors through the cloud. Increasingly, cloud services are being looked on as the method for providing access to quantum processing. Quantum computers achieve their massive computing power by initiating quantum physics into processing power and when users are allowed access to these quantum-powered computers through the internet it is known as quantum computing within the cloud.
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.
Monika Schleier-Smith is an American experimental physicist studying many-body quantum physics by precisely assembling systems of ultracold atoms. Her research helps connect the world of theoretical and experimental physics. These atomic, molecular, and optical physics (AMO) engineered systems have applications in quantum sensing, coherent control, and quantum computing. Schleier-Smith is an associate professor of physics at Stanford University, a Sloan Research Fellow, and a National Science Foundation CAREER Award recipient. Schleier-Smith also serves on the board of directors for the Hertz Foundation and also works to improve education through speaking and serving on panels.
Giuseppe Carleo is an Italian physicist. He is a professor of computational physics at EPFL and the head of the Laboratory of Computational Quantum Science.
The current state of quantum computing is referred to as the noisy intermediate-scale quantum (NISQ) era, characterized by quantum processors containing up to 1,000 qubits which are not advanced enough yet for fault-tolerance or large enough to achieve quantum advantage. 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.
A neutral atom quantum computer is a modality of quantum computers built out of Rydberg atoms; this modality has many commonalities with trapped-ion quantum computers. As of December 2023, the concept has been used to demonstrate a 48 logical qubit processor.
References
- ↑ "QuEraComputing/Bloqade.jl". Github. Retrieved 18 July 2023.
- 1 2 3 Russell, John (23 November 2022). "QuEra's Quest: Build a Flexible Neutral Atom-based Quantum Computer". HPCWire. Retrieved 18 July 2023.
- ↑ "QuEraComputing/GenericTensorNetworks.jl". Github. Retrieved 18 July 2023.
- ↑ Semeghini, Giulia; Levine, Harry; Keesling, Alexander; Ebadi, Sepehr; Wang, Tout; Bluvstein, Dolev; Verresen, Ruben; Pichler, Hannes; Kalinowski, Marcin; Samajdar, Rhine; Omran, Ahmed; Sachdev, Subir; Vishwanath, Ashvin; Greiner, Markus; Vuletić, Vladan; Lukin, Mikhail (Dec 2, 2021). "Probing topological spin liquids on a programmable quantum simulator". Science. 374 (6572): 1242–1247. arXiv: 2104.04119 . doi:10.1126/science.abi8794 . Retrieved 18 July 2023.
- ↑ Ebadi, Sepehr; Keesling, Alexander; Cain, Madelyn; Wang, Tout; Levine, Harry; Bluvstein, Dolev; Semeghini, Giulia; Omran, Ahmed; Liu, Jin-Guo; Samajdar, Rhine; Luo, Xiuzhe; Nash, Beatrice; Gao, Xun; Barak, Boaz; Farhi, Edward; Sachdev, Subir; Gemelke, Nathan; Zhou, Leo; Choi, Soonwon; Pichler, Hannes; Wang, Shengtao; Greiner, Markus; Vuletić, Vladan; Lukin, Mikhail (May 5, 2022). "Quantum optimization of maximum independent set using Rydberg atom arrays". Science. 376 (6598): 1209–1215. arXiv: 2202.09372 . doi:10.1126/science.abo6587.
- ↑ Park, Kate (17 November 2021). "QuEra Computing emerges from stealth with $17M to launch quantum device". TechCrunch. Retrieved 18 July 2023.
- ↑ Sullivan, Mark (17 November 2021). "This quantum computing startup says it's ready to take on IBM and Google". Fast Company. Retrieved 18 July 2023.
- ↑ Hu, Charlotte (10 February 2023). "How neutral atoms could help power next-gen quantum computers". Popular Science. Retrieved 18 July 2023.
- ↑ Bray, Hiawatha (2 November 2022). "Boston's QuEra Computing opens". Boston Globe. Retrieved 18 July 2023.
- ↑ Lee, Jane (2 November 2022). "Boston-based quantum computer QuEra joins Amazon's cloud for public access". Reuters. Retrieved 18 July 2023.
- ↑ Timmer, John. "Grid of atoms is both a quantum computer and an optimization solver". Ars Technica. Retrieved 18 July 2023.
- ↑ Nguyen, Minh-Thi; Liu, Jin-Guo; Wurtz, Jonathan; Lukin, Mikhail D.; Wang, Sheng-Tao; Pichler, Hannes (Feb 14, 2023). "Quantum Optimization with Arbitrary Connectivity Using Rydberg Atom Arrays". PRX Quantum. 4 (1): 010316. arXiv: 2209.03965 . doi:10.1103/PRXQuantum.4.010316 . Retrieved 18 July 2023.