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Qubit

About: Qubit is a research topic. Over the lifetime, 29978 publications have been published within this topic receiving 723084 citations. The topic is also known as: quantum bit & qbit.


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Journal ArticleDOI
TL;DR: A qubit readout scheme that exploits the Jaynes-Cummings nonlinearity of a superconducting cavity coupled to transmon qubits is demonstrated and there is the unexpected onset of a high-transmission "bright" state at a critical power which depends sensitively on the initial qubit state.
Abstract: We demonstrate a qubit readout scheme that exploits the Jaynes-Cummings nonlinearity of a superconducting cavity coupled to transmon qubits. We find that, in the strongly driven dispersive regime of this system, there is the unexpected onset of a high-transmission "bright" state at a critical power which depends sensitively on the initial qubit state. A simple and robust measurement protocol exploiting this effect achieves a single-shot fidelity of 87% using a conventional sample design and experimental setup, and at least 61% fidelity to joint correlations of three qubits.

295 citations

Journal ArticleDOI
David McKay1, Stefan Filipp1, Antonio Mezzacapo1, Easwar Magesan1, Jerry M. Chow1, Jay M. Gambetta1 
TL;DR: In this article, a resonant exchange interaction between two fixed-frequency superconducting qubits with a bus that is modulated at the frequency difference between the qubits was proposed.
Abstract: The authors address a critical scalability issue in quantum computer design by activating a resonant exchange interaction. They achieve this by coupling two fixed-frequency superconducting qubits with a bus that is modulated at the frequency difference between the qubits. This yields a high-fidelity iSWAP entangling gate, which is sought as an important component for fault-tolerant quantum circuits in the surface-code architecture. The general nature of the interaction also suggests applications in quantum simulation, annealing, and bath engineering.

294 citations

Journal ArticleDOI
TL;DR: In this article, a superconducting chip containing a regular array of flux qubits, tunable interqubit inductive couplers, an XY-addressable readout system, on-chip programmable magnetic memory, and a sparse network of analog control lines has been studied.
Abstract: A superconducting chip containing a regular array of flux qubits, tunable interqubit inductive couplers, an XY-addressable readout system, on-chip programmable magnetic memory, and a sparse network of analog control lines has been studied. The architecture of the chip and the infrastructure used to control it were designed to facilitate the implementation of an adiabatic quantum optimization algorithm. The performance of an eight-qubit unit cell on this chip has been characterized by measuring its success in solving a large set of random Ising spin-glass problem instances as a function of temperature. The experimental data are consistent with the predictions of a quantum mechanical model of an eight-qubit system coupled to a thermal environment. These results highlight many of the key practical challenges that we have overcome and those that lie ahead in the quest to realize a functional large-scale adiabatic quantum information processor.

294 citations

Journal ArticleDOI
TL;DR: In this paper, the authors construct quantum bits taking advantage of the topological protection and non-local properties of Majorana bound states (MBSs) in a network of parallel wires, but without relying on braiding for quantum gates.
Abstract: Quantum information protected by the topology of the storage medium is expected to exhibit long coherence times. Another feature is topologically protected gates generated through braiding of Majorana bound states (MBSs). However, braiding requires structures with branched topological segments which have inherent difficulties in the semiconductor–superconductor heterostructures now believed to host MBSs. In this paper, we construct quantum bits taking advantage of the topological protection and non-local properties of MBSs in a network of parallel wires, but without relying on braiding for quantum gates. The elementary unit is made from three topological wires, two wires coupled by a trivial superconductor and the third acting as an interference arm. Coulomb blockade of the combined wires spawns a fractionalized spin, non-locally addressable by quantum dots used for single-qubit readout, initialization, and manipulation. We describe how the same tools allow for measurement-based implementation of the Clifford gates, in total making the architecture universal. Proof-of-principle demonstration of topologically protected qubits using existing techniques is therefore within reach.

294 citations

Journal ArticleDOI
13 Oct 2017-Science
TL;DR: A high-frequency bulk acoustic wave resonator that is strongly coupled to a superconducting qubit using piezoelectric transduction with a cooperativity of 260 and quantum control and measurement on gigahertz phonons at the single-quantum level is experimentally demonstrated.
Abstract: Mechanical objects have important practical applications in the fields of quantum information and metrology as quantum memories or transducers for measuring and connecting different types of quantum systems The field of electromechanics is in pursuit of a robust and highly coherent device that couples motion to nonlinear quantum objects such as superconducting qubits Here, we experimentally demonstrate a high-frequency bulk acoustic wave resonator that is strongly coupled to a superconducting qubit using piezoelectric transduction with a cooperativity of 260 We measure qubit and mechanical coherence times on the order of 10 microseconds Our device requires only simple fabrication methods and provides controllable access to a multitude of phonon modes We demonstrate quantum control and measurement on gigahertz phonons at the single-quantum level

293 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
20231,977
20224,380
20213,014
20203,119
20192,594
20182,228