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We analyse a system composed of a qubit coupled to electromagnetic fields of two high quality quantum oscillators. Particular realization of such a system is the superconducting qubit coupled to a transmission-line resonator driven by two…

Mesoscale and Nanoscale Physics · Physics 2014-05-12 S. N. Shevchenko , G. Oelsner , Ya. S. Greenberg , P. Macha , D. S. Karpov , M. Grajcar , U. Hubner , A. N. Omelyanchouk , E. Il'ichev

Quantum enhanced receivers are endowed with resources to achieve higher sensitivities than conventional technologies. For application in optical communications, they provide improved discriminatory capabilities for multiple non-orthogonal…

We follow the passage from complex amplitude bistability to phase bistability in the driven dissipative Jaynes-Cummings oscillator. Quasidistribution functions in the steady state are employed, for varying qubit-cavity detuning and drive…

Quantum Physics · Physics 2017-01-26 Th. K. Mavrogordatos

For many quantum systems intended for information processing, one detects the logical state of a qubit by integrating a continuously observed quantity over time. For example, ion and atom qubits are typically measured by driving a cycling…

Quantum Physics · Physics 2023-10-03 Shawn Geller , Daniel C. Cole , Scott Glancy , Emanuel Knill

We propose a state-sensitive scheme to optically detect a single molecule without a closed transition, through strong coupling to a high-Q whispering-gallery mode high-Q resonator. A background-free signal can be obtained by detecting a…

Atomic Physics · Physics 2020-09-02 Ming Zhu , Yan-Cheng Wei , Chen-Lung Hung

We develop a potentially practical proposal for robust quantum state transfer (QST) between two superconducting qubits coupled by a coplanar waveguide (CPW) resonator. We show that the partial measurement could drastically enhance the…

Quantum Physics · Physics 2022-09-14 Yan-Ling Li , Yao Yao , Xing Xiao

We propose a fast scheme to generate Schr\"odinger cat states in a superconducting resonator using a continuously driven qubit without resorting to the dispersive regime, two-photon drives, or engineered two-photon dissipation. We provide…

Quantum Physics · Physics 2024-02-08 M. Ayyash , X. Xu , M. Mariantoni

We develop a general theory for multiphoton qubit-resonator interactions enhanced by a qubit drive. The interactions generate qubit-conditional operations in the resonator when the driving is near $n$-photon cross-resonance, namely, the…

Quantum Physics · Physics 2024-11-21 Mohammad Ayyash , Xicheng Xu , Sahel Ashhab , Matteo Mariantoni

We find that feedback control may induce "pseudo" nonlinear dynamics in a damped harmonic oscillator, whose centroid trajectory in the phase space behaves like a classical nonlinear system. Thus, similar to nonlinear amplifiers (e.g.,…

Quantum Physics · Physics 2015-05-14 Jing Zhang , Yu-xi Liu , Re-Bing Wu , Chun-Wen Li , Tzyh-Jong Tarn

A coupled system of a superconducting transmission line resonator with a semiconductor double quantum dot is analyzed. We simulate the phase shift of the microwave signal in the resonator, which is sensitive to the quantum dot qubit state…

Quantum Physics · Physics 2013-12-10 Zhe Guan

We study the asymptotic dynamics of a driven spin-boson system where the environment is formed by a broadened localized mode. Upon exploiting an exact mapping, an equivalent formulation of the problem in terms of a quantum two-state system…

Mesoscale and Nanoscale Physics · Physics 2009-11-10 M. C. Goorden , M. Thorwart , M. Grifoni

Superconducting qubits typically use a dispersive readout scheme, where a resonator is coupled to a qubit such that its frequency is qubit-state dependent. Measurement is performed by driving the resonator, where the transmitted resonator…

We give a concrete experimental scheme for engineering the insulator-superfluid transition of light in a one-dimensional (1-D) array of coupled superconducting stripline resonators. In our proposed architecture, the on-site interaction and…

Quantum Physics · Physics 2015-05-28 Chun-Wang Wu , Ming Gao , Zhi-Jiao Deng , Hong-Yi Dai , Ping-Xing Chen , Cheng-Zu Li

We propose an efficient decomposition scheme for a quantum receiver that attains the Helstrom bound in the low-photon regime for discriminating binary coherent states. Our method, which avoids feedback as used in Dolinar's case, breaks down…

The process of measurement of a phase qubit by a resonant microwave cavity is considered for various interactions between the qubit and the cavity. A novel quasiclassical approach is described based on adiabatic reversals of the qubit state…

We investigate a superconducting qubit coupled to a quantum acoustic system in a near resonant configuration. In our system we measure multiphonon transitions, whose spectrum reveals distinctly nonclassical features and thus provides direct…

Mesoscale and Nanoscale Physics · Physics 2024-03-05 Alpo Välimaa , Wayne Crump , Mikael Kervinen , Mika A. Sillanpää

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 present a readout method for superconducting flux qubits. The qubit quantum flux state can be measured by determining the Josephson inductance of an inductively coupled DC superconducting quantum interference device (DC-SQUID). We…

Superconductivity · Physics 2007-06-06 A. Lupascu , C. J. P. M. Harmans , J. E. Mooij

We discuss a scheme in which sequential state-discrimination measurements are performed on qudits to determine the quantum state in which they were initially prepared. The qudits belong to a set of nonorthogonal quantum states and hence…

Quantum Physics · Physics 2017-10-17 Mark Hillery , Jihane Mimih

The measurement of quantum states is one of the most important problems in quantum mechanics. We introduce a quantum state tomography technique in which the state of a qubit is reconstructed, while the qubit remains undetected. The key…