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Solving problems related to open quantum systems has attracted many interests. Here, we propose a variational quantum algorithm to find the steady state of open quantum systems. In this algorithm, we employ parameterized quantum circuits to…

Quantum Physics · Physics 2021-08-11 Huan-Yu Liu , Tai-Ping Sun , Yu-Chun Wu , Guo-Ping Guo

Creating highly spin-squeezed states for quantum metrology surpassing the standard quantum limit is a topic of great interest. Spin squeezing has been achieved by either entangling different atoms in an ensemble, or by controlling the…

Quantum Physics · Physics 2025-11-18 Youwei Zhang , Shenchao Jin , Junlei Duan , Klaus Mølmer , Guiying Zhang , Mingfeng Wang , Yanhong Xiao

We implement a scalable platform for quantum sensing comprising hundreds of sites capable of holding individual laser-cooled atoms and demonstrate the applicability of this single-quantum-system sensor array to magnetic-field mapping on a…

Quantum Physics · Physics 2024-03-11 Dominik Schäffner , Tobias Schreiber , Fabian Lenz , Malte Schlosser , Gerhard Birkl

The ability to engineer parallel, programmable operations between desired qubits within a quantum processor is central for building scalable quantum information systems. In most state-of-the-art approaches, qubits interact locally,…

Squeezed states are a versatile class of quantum states with applications ranging from quantum computing to high-precision detection. We propose a method for generating tunable squeezed states of light with multiple modes encoded in…

Quantum Physics · Physics 2022-04-22 Christian Drago , Agata M. Brańczyk

Entanglement forging based variational algorithms leverage the bi-partition of quantum systems for addressing ground state problems. The primary limitation of these approaches lies in the exponential summation required over the numerous…

We propose a variational approach for preparing entangled quantum states on quantum computers. The methodology involves training a unitary operation to match with a target unitary using the Fubini-Study distance as a cost function. We…

Quantum Physics · Physics 2023-07-03 Vu Tuan Hai , Nguyen Tan Viet , Le Bin Ho

Optical tweezer arrays have transformed atomic and molecular physics, now forming the backbone for a range of leading experiments in quantum computing, simulation, and metrology. Typical experiments trap tens to hundreds of atomic qubits,…

Quantum Physics · Physics 2025-11-13 Hannah J. Manetsch , Gyohei Nomura , Elie Bataille , Kon H. Leung , Xudong Lv , Manuel Endres

Entanglement generation and detection are two of the most sought-after goals in the field of quantum control. Besides offering a means to probe some of the most peculiar and fundamental aspects of quantum mechanics, entanglement in…

Mesoscale and Nanoscale Physics · Physics 2011-11-29 M. S. Rudner , L. M. K. Vandersypen , V. Vuletic , L. S. Levitov

Quantum metrology protocols using entangled states of large spin ensembles attempt to achieve measurement sensitivities surpassing the standard quantum limit (SQL), but in many cases they are severely limited by even small amounts of…

Quantum Physics · Physics 2023-11-06 Martin Koppenhöfer , Peter Groszkowski , A. A. Clerk

Quantum metrology and sensing seek advantage in estimating an unknown parameter of some quantum state or channel, using entanglement such as spin squeezing produced by one-axis twists or other quantum resources. In particular, qubit phase…

Quantum Physics · Physics 2024-05-29 Tyler G. Thurtell , Akimasa Miyake

We investigate the generation of quantum states for precision metrology in noisy two-level systems. These states are obtained by optimizing a variational quantum circuit to maximize the quantum Fisher information (QFI) of the output state…

Many quantum state preparation methods rely on a combination of dissipative quantum state initialization, followed by unitary evolution to a desired target state. Here we demonstrate the usefulness of quantum measurement as an additional…

Quantum Physics · Physics 2020-07-01 Byron Alexander , Hermann Uys , John J. Bollinger

This paper reviews quantum spin squeezing, which characterizes the sensitivity of a state with respect to an SU(2) rotation, and is significant for both entanglement detection and high-precision metrology. We first present various…

Quantum Physics · Physics 2011-11-29 Jian Ma , Xiaoguang Wang , C. P. Sun , Franco Nori

Entanglement is recognized as a key resource for quantum computation and quantum cryptography. For quantum metrology, the use of entangled states has been discussed and demonstrated as a means of improving the signal-to-noise ratio. In…

Quantum Physics · Physics 2007-05-23 C. F. Roos , M. Chwalla , K. Kim , M. Riebe , R. Blatt

As it has been demonstrated that trapped ion systems have unmatched long-lived quantum-bit (qubit) coherence and can support high-fidelity quantum manipulations, how to scale up the system size becomes an inevitable task for practical…

Quantum Physics · Physics 2020-04-23 Yu-Ching Shen , Guin-Dar Lin

Spin squeezing is a form of entanglement that reshapes the quantum projection noise to improve measurement precision. Here, we provide numerical and analytic evidence for the following conjecture: any Hamiltonian exhibiting finite…

Entangled photons are widely used in quantum technologies. Many photonic experiments generate them with probabilistic photon-pair sources that can be modeled as squeeze operators. In practice, these sources are usually treated in the…

Quantum Physics · Physics 2026-05-05 Carlos Ruiz-Gonzalez , Mario Krenn , Xuemei Gu

We propose a protocol for generating multi-particle entangled states using coherent manipulation of atoms trapped in an optical cavity. We show how entanglement can be adiabatically produced with two control beams and by exploiting…

Quantum Physics · Physics 2023-05-31 Rahul Sawant

Emerging quantum hardware provides new possibilities for quantum simulation. While much of the research has focused on simulating closed quantum systems, the real-world quantum systems are mostly open. Therefore, it is essential to develop…

Quantum Physics · Physics 2024-02-14 Huo Chen , Niladri Gomes , Siyuan Niu , Wibe Albert de Jong