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We study the problem of maximizing privacy of quantized sensor measurements by adding random variables. In particular, we consider the setting where information about the state of a process is obtained using noisy sensor measurements. This…

Systems and Control · Computer Science 2018-09-11 Carlos Murguia , Iman Shames , Farhad Farokhi , Dragan Nesic

Symmetry is a unifying concept in physics. In quantum information and beyond, it is known that quantum states possessing symmetry are not useful for certain information-processing tasks. For example, states that commute with a Hamiltonian…

Quantum Physics · Physics 2023-09-27 Margarite L. LaBorde , Soorya Rethinasamy , Mark M. Wilde

In the framework of quantum open systems, that is, simple quantum systems coupled to quantum baths, our aim is to characterize those actions of the quantum environment which give rise to dynamics dictated by classical noises. First, we…

Mathematical Physics · Physics 2019-07-23 Stephane Attal , Julien Deschamps , Clement Pellegrini

Recently, a measure for the non-Markovian behavior of quantum processes in open systems has been developed which is based on the quantification of the flow of information between the open system and its environment [Phys. Rev. Lett. 103,…

Quantum Physics · Physics 2015-05-18 Elsi-Mari Laine , Jyrki Piilo , Heinz-Peter Breuer

We present a formalism that accounts for the evolution of quantum states of travelling light pulses incident on and emanating from a local quantum scatterer such as an atom or a cavity. We assume non-dispersive asymptotic propagation of the…

Quantum Physics · Physics 2019-09-25 Alexander Holm Kiilerich , Klaus Mølmer

Given multiple copies of a mixed quantum state with an unknown, nondegenerate principal eigenspace, quantum state purification is the task of recovering a quantum state that is closer to the principal eigenstate. A streaming protocol…

Quantum Physics · Physics 2025-03-31 Daniel Grier , Debbie Leung , Zhi Li , Hakop Pashayan , Luke Schaeffer

Complex quantum systems and their various applications are susceptible to noise of coherent and incoherent nature. Characterization of noise and its sources is an open, key challenge in quantum technology applications, especially in terms…

We investigate the coherence and non-Markovianity of a quantum tunneling system whose barrier is fluctuated by a telegraph noise, and its energy gap is modulated by Gaussian noise. With the help of averaging method, the system dynamics are…

Quantum Physics · Physics 2022-08-18 Nisreen Mohammed Mahdi , Arzu Kurt , Ferdi Altintas

Quantum feedback can stabilize a two-level atom against decoherence (spontaneous emission), putting it into an arbitrary (specified) pure state. This requires perfect homodyne detection of the atomic emission, and instantaneous feedback.…

Quantum Physics · Physics 2009-11-06 Jin Wang , H. M. Wiseman , G. J. Milburn

We investigate the effect of conditional null measurements on a quantum system and find a rich variety of behaviors. Specifically, quantum dynamics with a time independent $H$ in a finite dimensional Hilbert space are considered with…

Quantum Physics · Physics 2022-06-20 Quancheng Liu , Klaus Ziegler , David A. Kessler , Eli Barkai

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 propose a novel dark matter detection scheme by leveraging quantum coherence across a network of multiple quantum sensors. This method effectively eliminates incoherent background noise, thereby significantly enhancing detection…

High Energy Physics - Phenomenology · Physics 2024-10-31 Jing Shu , Bin Xu , Yuan Xu

Quantum metrology pursues high-precision measurements of physical quantities by using quantum resources. However, the decoherence generally hinders its performance. Previous work found that the metrological error tends to diverge in the…

Quantum Physics · Physics 2021-11-04 Wei Wu , Jun-Hong An

We introduce a quantity called the coherence of purification which can be a measure of total quantumness for a single system. We prove that coherence of purification is always more than the coherence of the system. For a pure state, the…

Quantum Physics · Physics 2019-07-31 Arun Kumar Pati , Long-Mei Yang , Chiranjib Mukhopadhyay , Shao-Ming Fei , Zhi-Xi Wang

Quantum measurements and the associated state changes are properly described in the language of instruments. We investigate the properties of a time continuous family of instruments associated with the recently introduced family of general…

Quantum Physics · Physics 2021-01-04 Nina Megier , Walter T. Strunz , Kimmo Luoma

It is universally accepted that noise may bring order to complex nonequilibrium systems. Most strikingly, entirely new states not seen in the noiseless system can be induced purely by including multiplicative noise -- an effect known as…

Quantum Physics · Physics 2023-09-27 A. Chia , W. -K. Mok , C. Noh , L. C. Kwek

Do stochastic Schr\"odinger equations, also known as unravelings, have a physical interpretation? In the Markovian limit, where the system {\em on average} obeys a master equation, the answer is yes. Markovian stochastic Schr\"odinger…

Quantum Physics · Physics 2009-11-07 Jay Gambetta , H. M. Wiseman

The pure state space of Quantum Mechanics is investigated as Hermitian Symmetric Kaehler manifold. The classical principles of Quantum Mechanics (Quantum Superposition Principle, Heisenberg Uncertainty Principle, Quantum Probability…

Quantum Physics · Physics 2009-11-07 R. Cirelli , M. Gatti , A. Maniá

Quantum mechanics allows for light-matter setups that hold excitations without releasing them as light. Arising from destructive interference processes, they are best seen in a Tavis-Cummings-like setup where two-level atoms (or qubits) are…

Quantum Physics · Physics 2025-09-19 L. Theerthagiri , Rajesh Narayanan , R. Ganesh

Randomised measurements can efficiently characterise many-body quantum states by learning the expectation values of observables with low Pauli weights. In this paper, we generalise the theoretical tools of classical shadow tomography to the…

Quantum Physics · Physics 2026-02-05 Gregory A. L. White , Lloyd C. L. Hollenberg , Charles D. Hill , Kavan Modi