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We report on the first experimental realization of optimal linear-optical controlled phase gates for arbitrary phases. The realized scheme is entirely flexible in that the phase shift can be tuned to any given value. All such controlled…

Quantum Physics · Physics 2015-05-19 Karel Lemr , Antonin Cernoch , Jan Soubusta , Konrad Kieling , Jens Eisert , Miloslav Dusek

We analyse the design and optimisation of quantum logic circuits suitable for the experimental demonstration of a three-qubit quantum computation prototype based on optically-controlled, solid-state quantum logic gates. In these gates, the…

Quantum Physics · Physics 2009-10-12 A. Del Duce , S. Savory , P. Bayvel

We demonstrate a quantum error correction scheme that protects against accidental measurement, using an encoding where the logical state of a single qubit is encoded into two physical qubits using a non-deterministic photonic CNOT gate. For…

Quantum Physics · Physics 2008-11-26 J. L. O'Brien , G. J. Pryde , A. G. White , T. C. Ralph

We show that it is possible to reduce the number of two-qubit gates needed for the construction of an arbitrary controlled-unitary transformation by up to two times using a tunable controlled-phase gate. On the platform of linear optics,…

Quantum Physics · Physics 2015-04-22 Karel Lemr , Karol Bartkiewicz , Antonín Černoch , Miloslav Dušek , Jan Soubusta

This paper presents novel methods for optimizing multi-controlled quantum gates, which naturally arise in high-level quantum programming. Our primary approach involves rewriting $U(2)$ gates as $SU(2)$ gates, utilizing one auxiliary qubit…

Quantum Physics · Physics 2025-03-12 Evandro C. R. Rosa , Eduardo I. Duzzioni , Rafael de Santiago

Instantaneous nonlocal quantum computation refers to a process in which spacelike separated parties simulate a nonlocal quantum operation on their joint systems through the consumption of pre-shared entanglement. To prevent a violation of…

Quantum Physics · Physics 2025-06-25 Alvin Gonzales , Eric Chitambar

We generalize an efficient decomposition method for diagonal operators by Welch et al. to qudit systems. The phase-context aware method focusses on cascaded entanglers whose decomposition into multi-controlled INC-gates can be optimized by…

Quantum Physics · Physics 2016-06-01 Kerstin Beer , Friederike Anna Dziemba

Leveraging noise bias, where phase-flip errors dominate over bit-flips, can drastically reduce the hardware overhead of fault-tolerant quantum computation, but existing approaches require bias-preserving CNOT gates whose implementation…

Quantum Physics · Physics 2026-05-26 Christophe Vuillot , Diego Ruiz , Jérémie Guillaud , Mazyar Mirrahimi

The purpose of this paper is to present a theoretic and numerical study of utilizing squeezing and phase shift in coherent feedback control of linear quantum optical systems. A quadrature representation with built-in phase shifters is…

Quantum Physics · Physics 2012-06-19 Guofeng Zhang , Heung Wing Joseph Lee , Bo Huang , Hu Zhang

We introduce transversal dimension jump, a code-switching protocol for lifted product (LP) quantum low-density parity-check (qLDPC) codes across different chain-complex dimensions, enabling universal fault-tolerant quantum computation with…

Quantum Physics · Physics 2026-03-03 Christine Li , John Preskill , Qian Xu

Modular quantum computing architectures require error correction schemes that remain effective in the presence of noisy inter-processor operations. As such, minimizing the number of such operations on logical circuits partitioned across…

Quantum Physics · Physics 2026-04-24 Bruno Avritzer , Nathan Sankary

Hybridizing different physical systems or degrees of freedom offers significant advantages for realizing practical, universal, scalable, and fault-tolerant quantum computation (FTQC). Here, we propose optical FTQC schemes with low squeezing…

Quantum Physics · Physics 2025-03-27 Peilin Du

Implementations for quantum computing require fast single- and multi-qubit quantum gate operations. In the case of optically controlled quantum dot qubits theoretical designs for long-range two- or multi-qubit operations satisfying all the…

Mesoscale and Nanoscale Physics · Physics 2013-01-23 Dmitry Solenov , Sophia E. Economou , T. L. Reinecke

High-efficiency quantum information processing is equivalent to the fewest quantum resources and the simplest operations by means of logic qubit gates. Based on the reflection geometry of a single photon interacting with a three-level…

Quantum Physics · Physics 2022-10-20 Yi-Ming Wu , Gang Fan , Fang-Fang Du

We suggest an efficient scheme for quantum computation with linear optical elements utilizing "linked" photon states. The linked states are designed according to the particular quantum circuit one wishes to process. Once a linked-state has…

Quantum Physics · Physics 2009-11-10 Nadav Yoran , Benni Reznik

We experimentally demonstrate quantum process tomography of controlled-Z and controlled-NOT gates using capacitively-coupled superconducting phase qubits. These gates are realized by using the $|2\rangle$ state of the phase qubit. We obtain…

High-quality two-qubit gate operations are crucial for scalable quantum information processing. Often, the gate fidelity is compromised when the system becomes more integrated. Therefore, a low-error-rate, easy-to-scale two-qubit gate…

Quantum Physics · Physics 2020-12-24 Yuan Xu , Ji Chu , Jiahao Yuan , Jiawei Qiu , Yuxuan Zhou , Libo Zhang , Xinsheng Tan , Yang Yu , Song Liu , Jian Li , Fei Yan , Dapeng Yu

Increasing connectivity and decreasing qubit-state delocalization without compromising the speed and accuracy of elementary gate operations are topical challenges in the development of large-scale superconducting quantum computers. In this…

Quantum Physics · Physics 2026-03-12 Tuure Orell , Hao Hsu , Joona Andersson , Jani Tuorila , Frank Deppe , Hsiang-Sheng Ku

We propose a linear optical quantum computation scheme using time-frequency degree of freedom. In this scheme, a qubit is encoded in single-photon frequency combs, and manipulation of the qubits is performed using time-resolving detectors,…

Quantum Physics · Physics 2023-06-13 Tomohiro Yamazaki , Tomoaki Arizono , Toshiki Kobayashi , Rikizo Ikuta , Takashi Yamamoto