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Schr\"odinger cat states, which are superpositions of macroscopically distinct states, are potentially critical resources for upcoming quantum information technologies. In this paper, we introduce a scheme to generate entangled…

High Energy Physics - Theory · Physics 2024-08-14 Partha Nandi , Nandita Debnath , Subhajit Kala , A. S. Majumdar

We demonstrate that superpositions of coherent and displaced Fock states, also referred to as generalized Schr\"odinger cats cats, can be created by application of a nonlinear displacement operator which is a deformed version of the Glauber…

Parametric gates and processes engineered from the perspective of the static effective Hamiltonian of a driven system are central to quantum technology. However, the perturbative expansions used to derive static effective models may not be…

Cat qubits, for which logical $|0\rangle$ and $|1\rangle$ are coherent states $|\pm\alpha\rangle$ of a harmonic mode, offer a promising route towards quantum error correction. Using dissipation to our advantage so that photon pairs of the…

We identify a noise model that ensures the functioning of an echo state network employing a gate-based quantum computer for reservoir computing applications. Energy dissipation induced by amplitude damping drastically improves the…

Quantum Physics · Physics 2025-06-24 Francesco Monzani , Emanuele Ricci , Luca Nigro , Enrico Prati

We investigate the superposition of coherent states, emphasizing quantum states with distinct Wigner phase-space features relevant to quantum information applications. In this study, we introduce generalized versions of the compass state,…

Quantum Physics · Physics 2025-08-26 Tan Hailin , Naeem Akhtar , Gao Xianlong

Quantum correlations typically decrease with increasing noise, although classical correlators (CCors) may rise for a particular class of states with noise. To analyse the behavior of classical correlation (CC) in the presence of local…

Quantum Physics · Physics 2022-09-08 Tanoy Kanti Konar , Arghya Maity , Aditi Sen De

Classical-quantum computational complexity separations are an important motivation for the long-term development of digital quantum computers, but classical-quantum complexity equivalences are just as important in our present era of noisy…

Quantum Physics · Physics 2020-03-10 Jonathan E. Moussa

We have investigated the dynamics of quantum discord and entanglement for two qubits subject to independent global transverse and/or longitudinal memoryless noisy classical fields. Global transverse and/or longitudinal random fields are…

Quantum Physics · Physics 2012-11-28 Ferdi Altintas , Arzu Kurt , Resul Eryigit

Physical systems usually exhibit quantum behavior, such as superpositions and entanglement, only when they are sufficiently decoupled from a lossy environment. Paradoxically, a specially engineered interaction with the environment can…

The occurrence of revivals of quantum entanglement between separated open quantum systems has been shown not only for dissipative non-Markovian quantum environments but also for classical environments in absence of back-action. While the…

Quantum Physics · Physics 2017-07-25 Rosario Lo Franco , Giuseppe Compagno

We consider a system composed of a two-level system (i.e. a qubit) and a harmonic oscillator in the ultrastrong-coupling regime, where the coupling strength is comparable to the qubit and oscillator energy scales. Special emphasis is placed…

Quantum Physics · Physics 2010-04-20 S. Ashhab , Franco Nori

Quantum harmonic oscillators are central to many modern quantum technologies. We introduce a method to determine the frequency noise spectrum of oscillator modes through coupling them to a qubit with continuously driven…

Although quantum mechanics is a mature theory, fundamental problems discussed during its time of foundation have remained with us to this day. These problems are centered on the problematic relation between the quantum and classical worlds.…

Quantum Physics · Physics 2007-05-23 G. B. Lesovik , A. V. Lebedev , G. Blatter

We study the dynamics of a system comprising a single qubit interacting equally with $N$ qubits (a "spin star" system). Although this model can be solved exactly, the exact solution does not give much intuition for the dynamics of the…

Quantum Physics · Physics 2014-07-23 Shane Dooley , Timothy P. Spiller

We report a novel theoretical approach on the microwave-induced resistance oscillations based on the coherent states of the quantum harmonic oscillator. We first obtain an expression for the coherent states of driven-quantum harmonic…

Mesoscale and Nanoscale Physics · Physics 2023-06-22 Jesus Inarrea

We propose a realistic scheme of generating a traveling odd Schr$\"o$dinger cat state and a generalized entangled coherent state in circuit quantum electrodynamics (circuit-QED). A squeezed vacuum state is used as initial resource of…

Quantum Physics · Physics 2016-11-02 Jaewoo Joo , Su-Yong Lee , Jaewan Kim

Quantum error correction with biased-noise qubits can drastically reduce the hardware overhead for universal and fault-tolerant quantum computation. Cat qubits are a promising realization of biased-noise qubits as they feature an…

Quantum Physics · Physics 2024-10-07 Ronan Gautier , Alain Sarlette , Mazyar Mirrahimi

For the paradigmatic case of the damped quantum harmonic oscillator we present two measurement-based feedback schemes to control the stability of its fixed point. The first scheme feeds back a Pyragas-like time-delayed reference signal and…

Quantum Physics · Physics 2015-07-10 Philipp Strasberg , Gernot Schaller , Tobias Brandes

Quantum Schrodinger cat states are of great interest in quantum communications and quantum optics. These states are used in various scientific fields such as quantum computing, quantum error correction and high-precision measurements. The…

Quantum Physics · Physics 2022-01-12 D. V. Fastovets , Yu. I. Bogdanov , N. A. Bogdanova , V. F. Lukichev