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We show theoretically how a correlation of multiple measurements on a qubit undergoing pure dephasing can be expressed as environmental noise filtering. The measurement of such correlations can be used for environmental noise spectroscopy,…

Quantum Physics · Physics 2020-01-22 Fattah Sakuldee , Łukasz Cywiński

In this paper, we propose a scheme to eliminate the influence of noises on system dynamics, by means of a sequential unsharp measurements and unitary feedback operations. The unsharp measurements are carried out periodically during system…

Quantum Physics · Physics 2018-09-19 Du Ran , Ye-Hong Chen , Zhi-Cheng Shi , Zhen-Biao Yang , Jie Song , Yan Xia

We investigate evolution of quantum correlations in ensembles of two-qubit nuclear spin systems via nuclear magnetic resonance techniques. We use discord as a measure of quantum correlations and the Werner state as an explicit example. We…

Quantum Physics · Physics 2012-10-31 Hemant Katiyar , Soumya Singha Roy , T. S. Mahesh , Apoorva Patel

We quantify the impact of spatio-temporally correlated Gaussian quantum noise on frequency estimation by Ramsey interferometry. While correlations in a classical noise environment can be exploited to reduce uncertainty relative to the…

Quantum Physics · Physics 2018-08-31 Félix Beaudoin , Leigh M. Norris , Lorenza Viola

Meaningful quantum computing is currently bottlenecked by the error rates of current generation Noisy Intermediate Scale Quantum (NISQ) devices. To improve the fidelity of the quantum logic gates, it is essential to recognize the…

We have observed sub-Poissonian spin correlations generated by collisionally induced spin mixing in a spin-1 Bose-Einstein condensate. We measure a quantum noise reduction of -7 dB (-10 dB corrected for detection noise) below the standard…

Quantum Gases · Physics 2015-05-30 Eva M. Bookjans , Christopher D. Hamley , Michael S. Chapman

Entangled qubits transported through space is a key element in many prospective quantum information systems, from long-distance quantum communication to large modular quantum processors. The moving qubits are decohered by time- and…

Mesoscale and Nanoscale Physics · Physics 2024-09-09 Aleksandr S. Mokeev , Yu-Ning Zhang , Viatcheslav V. Dobrovitski

Single-electron tunneling processes through a double quantum dot can induce a lasing state in an electromagnetic resonator which is coupled coherently to the dot system. Here we study the noise properties of the transport current in the…

Mesoscale and Nanoscale Physics · Physics 2013-08-20 Jinshuang Jin , Michael Marthaler , Pei-Qing Jin , Dmitry Golubev , Gerd Schön

The decoherence of mixed electron-nuclear spin qubits is a topic of great current importance, but understanding is still lacking: while important decoherence mechanisms for spin qubits arise from quantum spin bath environments with slow…

Mesoscale and Nanoscale Physics · Physics 2015-05-26 S. J. Balian , Gary Wolfowicz , John J. L. Morton , T. S. Monteiro

We investigate different quantum parameter estimation scenarios in the presence of noise, and identify optimal probe states. For frequency estimation of local Hamiltonians with dephasing noise, we determine optimal probe states for up to 70…

Quantum Physics · Physics 2014-08-10 F. Fröwis , M. Skotiniotis , B. Kraus , W. Dür

Decoherence is ubiquitous, and poses a significant impediment to the observation of quantum phenomena, such as the measurement-induced entanglement phase transition (MIPT). In this work, we study entanglement transitions in quantum circuits…

Quantum Physics · Physics 2025-03-10 Vikram Ravindranath , Yiqiu Han , Xiao Chen

We study the noise properties and efficiency of a mesoscopic resonant-level conductor which is used as a quantum detector, in the regime where transport through the level is only partially phase coherent. We contrast models in which…

Mesoscale and Nanoscale Physics · Physics 2007-05-23 A. A. Clerk , A. D. Stone

Experimental tests for assessing the physical reality of the hypothetical wave modes of quantum vacuum with zero-point energy are of fundamental importance for quantum field theories and cosmology. Physical effects like the Casimir effect…

Quantum Physics · Physics 2019-12-25 C. S. Unnikrishnan

We study the performance of simple quantum error correcting codes with respect to correlated noise errors characterized by a finite correlation strength. Specifically, we consider bit flip (phase flip) noisy quantum memory channels and use…

Quantum Physics · Physics 2015-05-13 Carlo Cafaro , Stefano Mancini

Using a quantum detector, a superconductor-insulator-superconductor junction, we probe separately the emission and absorption noise in the quantum regime of a superconducting resonant circuit at equilibrium. At low temperature the resonant…

Mesoscale and Nanoscale Physics · Physics 2012-01-27 Julien Basset , Hélène Bouchiat , Richard Deblock

Quantum coherence, the physical property underlying fundamental phenomena such as multi-particle interference and entanglement, has emerged as a valuable resource upon which modern technologies are founded. In general, the most prominent…

We investigate the time-evolution of a charge qubit subject to quantum telegraph noise produced by a single electronic defect level. We obtain results for the time-evolution of the coherence that are strikingly different from the usual case…

Mesoscale and Nanoscale Physics · Physics 2008-06-25 Benjamin Abel , Florian Marquardt

Despite being one of the hallmarks of quantum physics, there is a lack of operational interpretations of quantum coherence. Here we provide an operational interpretation of coherence of a quantum system, in terms of the amount of noise that…

Quantum Physics · Physics 2017-04-10 Uttam Singh , Manabendra Nath Bera , Avijit Misra , Arun Kumar Pati

Quantum metrology seeks to leverage the richness of quantum systems for making better measurements than are possible using only classical resources in order to gain a ``quantum advantage''. Quantum metrology schemes must also be resilient…

Quantum synchronization offers new possibilities for the exploration of collective dynamics in many-body systems. However, achieving synchronization in many-body quantum systems still faces numerous challenges. Here, we focus on the…

Quantum Physics · Physics 2025-06-24 Zhan-Ting Zhang , Gao-Ying Bo , Fu-Quan Dou