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We analyse the entanglement structure of states generated by random constant-depth two-dimensional quantum circuits, followed by projective measurements of a subset of sites. By deriving a rigorous lower bound on the average entanglement…

Quantum Physics · Physics 2025-05-21 Max McGinley , Wen Wei Ho , Daniel Malz

Measurements are essential for the processing and protection of information in quantum computers. They can also induce long-range entanglement between unmeasured qubits. However, when post-measurement states depend on many non-deterministic…

We present a general technique for deterministic implementation of a multi-mode nonlinear coupling between several propagating microwave or optical modes in quantum circuits. The measurement induced technique combines specifically prepared…

Quantum Physics · Physics 2021-01-07 Seckin Sefi , Petr Marek , Radim Filip

We study frustration-free control, a measurement-feedback protocol for quantum state preparation that extends the concept of frustration-free Hamiltonians to stochastic dynamics. The protocol drives many-body systems into highly entangled…

Quantum Physics · Physics 2026-04-06 T. Dörstel , T. Iadecola , J. H. Wilson , M. Buchhold

This work investigates variational compilation methods for simulating quantum systems with internal SU(2) symmetry. The central component of the research is the application of the Dynamic Mode Decomposition (DMD) method to extrapolate…

Quantum Physics · Physics 2025-06-26 Oleksa Hryniv

We consider dual unitary operators and their multi-leg generalizations that have appeared at various places in the literature. These objects can be related to multi-party quantum states with special entanglement patterns: the sites are…

Quantum Physics · Physics 2022-10-25 Márton Mestyán , Balázs Pozsgay , Ian M. Wanless

A fundamental distinction between many-body quantum states are those with short- and long-range entanglement (SRE and LRE). The latter cannot be created by finite-depth circuits, underscoring the nonlocal nature of Schr\"odinger cat states,…

Strongly Correlated Electrons · Physics 2024-06-11 Nathanan Tantivasadakarn , Ryan Thorngren , Ashvin Vishwanath , Ruben Verresen

Motivated by the expectation that relativistic symmetries might acquire quantum features in Quantum Gravity, we take the first steps towards a theory of ''Doubly'' Quantum Mechanics, a modification of Quantum Mechanics in which the…

Quantum Physics · Physics 2025-04-30 Vittorio D'Esposito , Giuseppe Fabiano , Domenico Frattulillo , Flavio Mercati

Entangled multi-qubit states may be generated through a dispersive collective QND measurement of superconducting qubits coupled to a microwave transmission line resonator. Using the quantum trajectory approach, we analyze the stochastic…

Mesoscale and Nanoscale Physics · Physics 2013-05-29 Ferdinand Helmer , Florian Marquardt

We present protocols for preparing two-dimensional abelian and non-abelian topologically ordered states by employing finite depth unitary circuits composed of long-ranged, simultaneous, and mutually commuting two-qubit gates. Our protocols…

Quantum Physics · Physics 2024-10-16 Yarden Sheffer , Erez Berg , Ady Stern

Quantum advantage schemes probe the boundary between classically simulatable and classically intractable quantum dynamics. We explore the impact of mid-circuit measurements on the computational power of quantum circuits. To this effect, we…

Quantum Physics · Physics 2026-03-24 Chenfeng Cao , Jens Eisert

Quantum systems evolve in time in one of two ways: through the Schr\"odinger equation or wavefunction collapse. So far, deterministic control of quantum many-body systems in the lab has focused on the former, due to the probabilistic nature…

We provide several examples and an intuitive diagrammatic representation demonstrating the use of two-qubit unitary transformations for mapping coupled spin Hamiltonians to simpler ones and vice versa. The corresponding dualities may be…

Quantum Physics · Physics 2016-06-01 Gernot Schaller , Ralf Schützhold

Quantum squeezed states offer metrological enhancement as compared to their classical counterparts. Here, we devise and numerically explore a novel method for performing SU(1,1) interferometry beyond the standard quantum limit, using…

Quantum Gases · Physics 2023-09-25 Ivor Krešić , Thorsten Ackemann

Quantum measurements performed on a subsystem of a quantum many-body state can generate entanglement for its remaining constituents. The whole system including the measurement record is described by a hybrid mixed state, which can exhibit…

Quantum Physics · Physics 2026-01-01 Qingyuan Wang , Romain Vasseur , Simon Trebst , Andreas W. W. Ludwig , Guo-Yi Zhu

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

An important conjecture within the AdS/CFT correspondence relates holographic spacetime to the quantum computational complexity of the dual quantum field theory. However, the quantitative understanding of this relation is still an open…

High Energy Physics - Theory · Physics 2022-12-02 Johanna Erdmenger , Marius Gerbershagen , Michal P. Heller , Anna-Lena Weigel

Dynamic quantum circuits incorporate mid-circuit measurements and feed-forward operations originally intended to realize Quantum Error Correction. This paradigm has recently been utilized to prepare certain states and long-range entangling…

A dual-rate control system is a hybrid system composed of continuous-time and discrete-time elements with two sampling frequencies. In this work, a new frequency domain analysis and design approach, based on the Quantitative Feedback Theory…

Systems and Control · Electrical Eng. & Systems 2020-02-11 Alfonso Baños , Julián Salt , Vicente Casanova

A powerful tool emerging from the study of many-body quantum dynamics is that of dual-unitary circuits, which are unitary even when read `sideways', i.e., along the spatial direction. Here, we show that this provides the ideal framework to…

Quantum Physics · Physics 2024-06-25 David T. Stephen , Wen Wei Ho , Tzu-Chieh Wei , Robert Raussendorf , Ruben Verresen