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We investigate the violation of non-contextuality by a class of continuous variable states, including variations of entangled coherent states (ECS's) and a two-mode continuous superposition of coherent states. We generalise the…

Quantum Physics · Physics 2015-05-27 Gerard McKeown , Matteo G. A. Paris , Mauro Paternostro

The coherent control of multi-partite quantum systems presents one of the central prerequisites in state-of-the-art quantum information processing. With the added benefit of inherent high-fidelity detection capability, atomic quantum…

Quantum Physics · Physics 2022-12-07 Jan Schütz , Alexander Martin , Sanah Laschinger , Gerhard Birkl

Collective coherent (CC) errors are inevitable, as every physical qubit undergoes free evolution under its kinetic Hamiltonian. These errors can be more damaging than stochastic Pauli errors because they affect all qubits coherently,…

Quantum Physics · Physics 2025-11-14 En-Jui Chang

We experimentally demonstrate that loop state-preparation-and-measurement (SPAM) tomography is capable of detecting correlated errors in a two-qubit system. We prepare photon pairs in a state that approximates a Werner state, which may or…

Quantum Physics · Physics 2018-07-11 M. E. Feldman , G. K. Juul , S. J. Van Enk , M. Beck

We use the probability of error as a measure of distinguishability between two pure and two mixed symmetric coherent states in the context of continuous variable quantum cryptography. We show that the two mixed symmetric coherent states (in…

Quantum Physics · Physics 2007-05-23 Christian Weedbrook , Mile Gu , Andrew M. Lance , Thomas Symul , Ping Koy Lam , Timothy C. Ralph

A ray of photons, emitted from a laser source, is in a coherent state, where macroscopic number of photons are degenerate in the same quantum state. The coherent state has degrees of freedom for spin and orbital angular momentum, which…

Optics · Physics 2024-07-23 Shinichi Saito

Gaussian bipartite states are basic tools for the realization of quantum information protocols with continuous variables. Their complete characterization is obtained by the reconstruction of the corresponding covariance matrix. Here we…

Quantum Physics · Physics 2016-04-27 D. Buono , G. Nocerino , V. D'Auria , A. Porzio , S. Olivares , M. G. A. Paris

We propose a scheme involving a Cooper pair transistor (CPT) embedded in a superconducting microwave cavity, where the CPT serves as a charge tunable quantum inductor to facilitate ultra-strong coupling between photons in the cavity and a…

Mesoscale and Nanoscale Physics · Physics 2014-05-13 A. J. Rimberg , M. P. Blencowe , A. D. Armour , P. D. Nation

We propose novel coherent-state phase concentration by probabilistic measurement-induced ampli- fication. The amplification scheme uses novel architecture, thermal noise addition (instead of single photon addition) followed by feasible…

Quantum Physics · Physics 2015-05-13 Petr Marek , Radim Filip

Optical supercavity modes (superstates), i.e., hybrid modes emerging from the strong coupling of two nonorthogonal modes of an open cavity, can support ultranarrow lines in scattering spectra associated with quasi bound states in the…

Optics · Physics 2020-07-29 Nikita Nefedkin , Andrea Alú , Alex Krasnok

Coherent signal containing squeezed noise in a mixed state of radiation field is considered here as a non-Gaussian mixture of a coherent state density operator and a squeezed state density operator, as opposed to the usual well known…

Quantum Physics · Physics 2024-07-18 Koushik Mandal , Pooja Jethwani , M. Venkata Satyanarayana

There is growing evidence that the unconventional spatial inhomogeneities in the doped high-Tc superconductors are accompanied by the pairing of electrons, subsequent quantum phase transitions (QPTs), and condensation in coherent states. We…

Strongly Correlated Electrons · Physics 2012-11-12 Kun Fang , G. W. Fernando , A. V. Balatsky , A. N. Kocharian , Kalum Palandage

Present work is an attempt to compare quantum discord and quantum entanglement of Werner states formed with the four bipartite entangled coherent states (ECS) used recently for quantum teleportation of a qubit encoded in superposed coherent…

Quantum Physics · Physics 2012-09-18 Manoj K. Mishra , Ajay K. Maurya , Hari Prakash

The discrimination of non-orthogonal quantum states with reduced or without errors is a fundamental task in quantum measurement theory. In this work, we investigate a quantum measurement strategy capable of discriminating two coherent…

Quantum Physics · Physics 2010-10-12 Christoffer Wittmann , Ulrik L. Andersen , Gerd Leuchs

We investigate the stability of logical information in quantum stabilizer codes subject to coherent unitary errors. Beginning with a logical state, we apply a random unitary error channel and subsequently measure stabilizer checks,…

Quantum Physics · Physics 2026-04-10 Hanchen Liu , Xiao Chen

We propose a pulse and continuous wave (CW) hybrid architecture of continuous-variable measurement-based optical quantum computation utilizing the strengths of both pulsed and CW light. In this architecture, input and ancillary non-Gaussian…

We present a detailed report on the decoherence of quantum states of continuous variable systems under the action of a quantum optical master equation resulting from the interaction with general Gaussian uncorrelated environments. The rate…

Quantum Physics · Physics 2007-05-23 A. Serafini , M. G. A. Paris , F. Illuminati , S. De Siena

A cat-state is a superposition of two coherent states with amplitudes $\alpha_{0}$ and $-\alpha_{0}$. Recent experiments create cat states in a microwave cavity field using superconducting circuits. As with degenerate parametric oscillation…

Quantum Physics · Physics 2021-01-04 R. Y. Teh , P. D. Drummond , M. D. Reid

Entangled coherent states can be prepared remotely by subtracting non-locally a single photon from two quantum superpositions of coherent states, the so-called "Schroedinger's cat" state. Such entanglement can further be distributed over…

We propose a new scheme of measurement-based quantum computation (MBQC) using an error-correcting code against photon-loss in circuit quantum electrodynamics. We describe a specific protocol of logical single-qubit gates given by sequential…

Quantum Physics · Physics 2019-12-17 Jaewoo Joo , Chang-Woo Lee , Shingo Kono , Jaewan Kim