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The introduction of phase coherence in the detection of quantum noise of light yields a pure quantum measurement of spectral modes. We theoretically show that such coherent quantum measurement performed with the technique of resonator…

Quantum Physics · Physics 2015-12-21 F. A. S. Barbosa , A. S. Coelho , K. N. Cassemiro , M. Martinelli , P. Nussenzveig , A. S. Villar

The paper deals with quantum pulse position modulation (PPM), both in the absence (pure states) and in the presence (mixed states) of thermal noise, using the Glauber representation of coherent laser radiation. The objective is to find…

Quantum Physics · Physics 2009-11-16 G. Cariolaro , G. Pierobon

By exploiting the exotic quantum states of a probe, it is possible to realize efficient sensors that are attractive for practical metrology applications and fundamental studies. Similar to other quantum technologies, quantum sensing is…

Quantum Physics · Physics 2022-07-06 W. Wang , Z. -J. Chen , X. Liu , W. Cai , Y. Ma , X. Mu , L. Hu , Y. Xu , H. Wang , Y. P. Song , X. -B. Zou , C. -L. Zou , L. Sun

Large-scale optimization problems are prevalent in several fields, including engineering, finance, and logistics. However, most optimization problems cannot be efficiently encoded onto a physical system because the existing quantum samplers…

Generalized quantum measurements are an important extension of projective or von Neumann measurements, in that they can be used to describe any measurement that can be implemented on a quantum system. We describe how to realize two…

Quantum sensing is an emerging field with the potential to outperform classical methods in both precision and spatial resolution. However, the sensitivity of the underlying quantum platform also makes the sensors highly susceptible to their…

Quantum Physics · Physics 2025-12-15 Miriam Resch , Dennis Herb , Mirko Rossini , Joachim Ankerhold , Dominik Maile

Quantum error correction is required to compensate for the fragility of the state of a quantum computer. We report the first experimental implementations of quantum error correction and confirm the expected state stabilization. In NMR…

Quantum Physics · Physics 2009-10-31 D. G. Cory , W. Mass , M. Price , E. Knill , R. Laflamme , W. H. Zurek , T. F. Havel , S. S. Somaroo

Quantum computing using two optical coherent states as qubit basis states has been suggested as an interesting alternative to single photon optical quantum computing with lower physical resource overheads. These proposals have been…

Quantum Physics · Physics 2009-11-13 A. P. Lund , T. C. Ralph , H. L. Haselgrove

The optical phase shifter that constantly rotates the local oscillator phase is a necessity in continuous-variable quantum key distribution systems with heterodyne detection. In previous experimental implementations, the optical phase…

Quantum Physics · Physics 2021-09-29 Tao Shen , Yundi Huang , Xiangyu Wang , Huiping Tian , Ziyang Chen , Song Yu

Quantum metrology promises high-precision measurements beyond the capability of any classical techniques, and has the potential to be integral to investigative techniques. However, all sensors must tolerate imperfections if they are to be…

We introduce a feedback control algorithm that increases the speed at which a measurement extracts information about a $d$-dimensional system by a factor that scales as $d^2$. Generalizing this algorithm, we apply it to a register of $n$…

Quantum Physics · Physics 2009-08-15 Joshua Combes , Howard M. Wiseman , Kurt Jacobs

The paper investigates the techniques of quantum computation in metrological predictions, with a particular emphasis on enhancing prediction potential through variational parameter estimation. The applicability of quantum simulations and…

Quantum Physics · Physics 2025-01-31 Vaidik A Sharma , N. Madurai Meenachi , B. Venkatraman

Classical sensors for spectrum analysis are widely used but lack micro- or nanoscale spatial resolution. On the other hand, quantum sensors, capable of working with nanoscale precision, do not provide precise frequency resolution over a…

Quantum Physics · Physics 2022-07-12 Nicolas Staudenmaier , Simon Schmitt , Liam P. McGuinness , Fedor Jelezko

The readout error on near-term quantum devices is one of the dominant noise factors, which can be mitigated by classical postprocessing called quantum readout error mitigation (QREM). The standard QREM applies the inverse of noise…

Quantum Physics · Physics 2025-05-16 Bo Yang , Rudy Raymond , Shumpei Uno

We present a simple formalism describing evolution of a qubit in the process of its measurement in a circuit QED setup. When a phase-sensitive amplifier is used, the evolution depends on only one output quadrature, and the formalism is the…

Quantum Physics · Physics 2012-05-11 Alexander N. Korotkov

Quantum mechanics establishes the ultimate limit to the scaling of the precision on any parameter, by iden- tifying optimal probe states and measurements. While this paradigm is, at least in principle, adequate for the metrology of quantum…

Variational Quantum Algorithms (VQAs) are a promising application for near-term quantum processors, however the quality of their results is greatly limited by noise. For this reason, various error mitigation techniques have emerged to deal…

Quantum Physics · Physics 2020-10-19 George S. Barron , Christopher J. Wood

The sensitivity of classical and quantum sensing is impaired in a noisy environment. Thus, one of the main challenges facing sensing protocols is to reduce the noise while preserving the signal. State of the art quantum sensing protocols…

Optics · Physics 2016-07-18 L. Cohen , Y. Pilnyak , D. Istrati , A. Retzker , H. S. Eisenberg

Quantum interferometers offer phase measurement capabilities that surpass the standard quantum limit (SQL), with phase sensitivity and quantum enhancement factor serving as key performance metrics. However, practical implementations face…

Quantum Physics · Physics 2026-01-27 Jie Zhao , Zeliang Wu , Haoran Liu , Yueya Liu , Xin Chen , Xinyun Liang , Wenfeng Huang , Chun-Hua Yuan , L. Q. Chen

Radiation impacts are a current challenge with computing on superconducting-based quantum devices because they can lead to widespread correlated errors across the device. Such errors can be problematic for quantum error correction (QEC)…