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Photonic integrated circuits play a central role in current and future applications such as communications, sensing, ranging, and information processing. Photonic quantum computing will also likely require an integrated optics architecture…

We use the numerical optimization techniques of Uskov et al. [PRA 81, 012303 (2010)] to investigate the behavior of the success rates for KLM style [Nature 409, 46 (2001)] two- and three-qubit entangling gates. The methods are first…

Quantum Physics · Physics 2012-07-10 A. Matthew Smith , D. B. Uskov , L. H. Ying , L. Kaplan

Universal quantum gates lie at the heart of designing quantum computer. We construct two compact quantum circuits to implement post-selected controlled-phase-flip (CPF) gate and Toffoli gate with linear optics assisted by one and two single…

Quantum Physics · Physics 2022-11-18 Wen-Qiang Liu , Hai-Rui Wei

Quantum computation requires qubits that can be coupled and realized in a scalable manner, together with universal and high-fidelity one- and two-qubit logic gates \cite{DiVincenzo2000, Loss1998}. Strong effort across several fields have…

Deterministic photon-photon gates enable the controlled generation of entanglement between mobile carriers of quantum information. Such gates have thus far been exclusively realized in the optical domain and by relying on post-selection.…

Arbitrarily accurate fault-tolerant (FT) universal quantum computation can be carried out using the Clifford gates Z, S, CNOT plus the non-Clifford T gate. Moreover, a recent improvement of the Solovay-Kitaev theorem by Kuperberg implies…

Quantum Physics · Physics 2024-07-02 H. F. Chau

We analyze the detection of itinerant photons using a quantum non-demolition (QND) measurement. We show that the backaction due to the continuous measurement imposes a limit on the detector efficiency in such a scheme. We illustrate this…

Mesoscale and Nanoscale Physics · Physics 2013-05-29 Ferdinand Helmer , Matteo Mariantoni , Enrique Solano , Florian Marquardt

In our earlier work we posited that simple quantum gates and quantum algorithms can be designed utilizing the diffraction phenomena of a photon within a multiplexed holographic element. The quantum eigenstates we use are the photon's…

Quantum Physics · Physics 2015-12-18 Paul M. Alsing , Grigoriy Kreymerman , Warner A. Miller

We demonstrate how gradient ascent pulse engineering optimal control methods can be implemented on donor electron spin qubits in Si semiconductors with an architecture complementary to the original Kane's proposal. We focus on the…

Mesoscale and Nanoscale Physics · Physics 2015-05-13 Dong-Bang Tsai , Po-Wen Chen , Hsi-Sheng Goan

Gate fidelity -- an average fidelity over all possible input states -- is the workhorse metric for benchmarking quantum gates or circuits, yet fault-tolerant quantum computing ultimately depends on the worst-case behavior, typically…

Quantum Physics · Physics 2026-03-10 Kyoungho Cho , Ilkwon Sohn , Yongsoo Hwang , Jeongho Bang

We report the first experimental demonstration of a quantum controlled-NOT gate for different photons, which is classically feed-forwardable. In the experiment, we achieved this goal with the use only of linear optics, an entangled…

Quantum Physics · Physics 2009-11-10 Sara Gasparoni , Jian-Wei Pan , Philip Walther , Terry Rudolph , Anton Zeilinger

We propose a geometric phase gate of two ion qubits that are encoded in two levels linked by an optical dipole-forbidden transition. Compared to hyperfine geometric phase gates mediated by electric dipole transitions, the gate has many…

Quantum Physics · Physics 2008-05-16 K. Kim , C. F. Roos , L. Aolita , H. Haeffner , V. Nebendahl , R. Blatt

In this paper, we examine various software and hardware strategies for implementing high-fidelity controlled-Z gate in the large-scale quantum system by solving the system's Hamiltonian with the Lindblad master equation. First, we show that…

Quantum Physics · Physics 2022-12-09 Dowon Baek , Seong Hyeon Park , Suhwan Choi , Chanwoo Yoo , Seungyong Hahn

Bosonic codes offer hardware-efficient approaches to logical qubit construction and hosted the first demonstration of beyond-break even logical quantum memory. However, such accomplishments were done for idling information, and realization…

Quantum Physics · Physics 2026-04-08 Saswata Roy , Owen C. Wetherbee , Valla Fatemi

High fidelity quantum operations are key to enabling fault-tolerant quantum computation. Superconducting quantum processors have demonstrated high-fidelity operations, but on larger devices there is commonly a broad distribution of…

The continuous-variable controlled-Z gate is a canonical two-mode gate for universal continuous-variable quantum computation. It is considered as one of the most fundamental continuous-variable quantum gates. Here we present a scheme for…

Quantum Physics · Physics 2015-05-27 Ming-Feng Wang , Nian-Quan Jiang , Qing-Li Jin , Yi-Zhuang Zheng

High fidelity two-qubit gates exhibiting low crosstalk are essential building blocks for gate-based quantum information processing. In superconducting circuits two-qubit gates are typically based either on RF-controlled interactions or on…

Harnessing the unique properties of quantum mechanics offers the possibility to deliver new technologies that can fundamentally outperform their classical counterparts. These technologies only deliver advantages when components operate with…

We study the cross-resonance effect in capacitively-coupled fluxonium qubits and devise a simple formula for their maximum ZX interaction strength. By going beyond the perturbative regime, we find that a CNOT gate can generally be realized…

Quantum Physics · Physics 2026-03-19 Eugene Y. Huang , Christian Kraglund Andersen

A new approach to efficient quantum computation with probabilistic gates is proposed and analyzed in both a local and non-local setting. It combines heralded gates previously studied for atom or atom-like qubits with logical encoding from…

Quantum Physics · Physics 2017-04-19 Johannes Borregaard , Anders S. Sørensen , Ignacio Cirac , Mikhail D. Lukin