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We present a low-depth amplitude encoding method for arbitrary quantum state preparation. Building on the foundation of an existing divide-and-conquer algorithm, we propose a method to disentangle the ancillary qubits from the final state.…

Quantum Physics · Physics 2025-10-10 Roselyn Nmaju , Fiona Speirits , Sarah Croke

Adaptive quantum circuits, which combine local unitary gates, midcircuit measurements, and feedforward operations, have recently emerged as a promising avenue for efficient state preparation, particularly on near-term quantum devices…

Quantum Physics · Physics 2025-04-01 Kevin C. Smith , Abid Khan , Bryan K. Clark , S. M. Girvin , Tzu-Chieh Wei

This thesis explores the use of entangled states in quantum computation and quantum information science. Entanglement, a quantum phenomenon with no classical counterpart, has been identified as an important and quantifiable resource in many…

Quantum Physics · Physics 2008-08-12 Hyeyoun Chung

Variational quantum algorithms (VQAs) face an inherent trade-off between expressivity and trainability: deeper circuits can represent richer states but suffer from noise accumulation and barren plateaus, while shallow circuits remain…

Quantum Physics · Physics 2025-10-31 Shaojun Wu , Shan Jin , Abolfazl Bayat , Xiaoting Wang

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…

We introduce protocols to prepare many-body quantum states with quantum circuits assisted by local operations and classical communication. We show that by lifting the requirement of exact preparation, one can substantially save resources.…

Quantum Physics · Physics 2024-12-04 Lorenzo Piroli , Georgios Styliaris , J. Ignacio Cirac

We consider the transformations of quantum states obtainable by a process of the following sort. Combine the given input state with a specially prepared initial state of an auxiliary system. Apply a unitary transformation to the combined…

Quantum Physics · Physics 2015-10-13 Andreas Blass , Yuri Gurevich

We develop an adaptive method for quantum state preparation that utilizes randomness as an essential component and that does not require classical optimization. Instead, a cost function is minimized to prepare a desired quantum state…

Quantum Physics · Physics 2023-10-10 Alicia B. Magann , Sophia E. Economou , Christian Arenz

The concept of entanglement and separability of quantum states is relevant for several fields in physics. Still, there is a lack of effective operational methods to characterise these features. We propose a method to certify quantum…

Quantum Physics · Physics 2024-03-06 Ties-A. Ohst , Xiao-Dong Yu , Otfried Gühne , H. Chau Nguyen

Learning quantum states from measurement data is a central problem in quantum information and computational complexity. In this work, we study the problem of learning to generate mixed states on a finite-dimensional lattice. Motivated by…

An extension to computational mechanics complexity measure is proposed in order to tackle quantum states complexity quantification. The method is applicable to any $n-$partite state of qudits through some simple modifications. A Werner…

Computational Physics · Physics 2011-10-28 Yuri Campbell , José Roberto Castilho Piqueira

Quantum entanglement is the quantum information processing resource. Thus it is of importance to understand how much of entanglement particular quantum states have, and what kinds of laws entanglement and also transformation between…

Quantum Physics · Physics 2007-05-23 Toshiyuki Shimono

Understanding the complexity of quantum states and circuits is a central challenge in quantum information science, with broad implications in many-body physics, high-energy physics and quantum learning theory. A common way to model the…

Quantum Physics · Physics 2026-05-15 Oxana Shaya , Zoë Holmes , Christoph Hirche , Armando Angrisani

We investigate notions of complexity of states in continuous quantum-many body systems. We focus on Gaussian states which include ground states of free quantum field theories and their approximations encountered in the context of the…

High Energy Physics - Theory · Physics 2018-11-15 Shira Chapman , Michal P. Heller , Hugo Marrochio , Fernando Pastawski

We initiate the study of state complexity for continuous-variable quantum systems. Concretely, we consider a setup with bosonic modes and auxiliary qubits, where available operations include Gaussian one- and two-mode operations, single-…

Quantum Physics · Physics 2025-11-06 Lukas Brenner , Libor Caha , Xavier Coiteux-Roy , Robert Koenig

We introduce a quantifier of phase-space complexity for discrete-variable (DV) quantum systems. Motivated by a recent framework developed for continuous-variable systems, we construct a complexity measure of quantum states based on the…

Quantum Physics · Physics 2026-03-05 Siting Tang , Shunlong Luo , Matteo G. A. Paris

Estimating the state preparation fidelity of highly entangled states on noisy intermediate-scale quantum (NISQ) devices is important for benchmarking and application considerations. Unfortunately, exact fidelity measurements quickly become…

Quantum Physics · Physics 2025-01-29 Shamminuj Aktar , Andreas Bärtschi , Abdel-Hameed A. Badawy , Stephan Eidenbenz

We present a theoretical framework for state-adaptive quantum error correction that bridges the gap between quantum computing and error correction paradigms. By incorporating knowledge of quantum states into the error correction process, we…

Quantum Physics · Physics 2026-02-02 D. -S. Wang

Circuit complexity for two-dimensional topological quantum field theories (2D TQFT) was defined by Couch, Fan, and Shashi in [12]. In this paper, we study complexity for the 2D TQFT given by quantum cohomology of compact symplectic…

Algebraic Geometry · Mathematics 2026-03-04 Xiaobo Liu , Chongyu Wang

The degree to which a pure quantum state is entangled can be characterized by the distance or angle to the nearest unentangled state. This geometric measure of entanglement is explored for bi-partite and multi-partite pure and mixed states.…

Quantum Physics · Physics 2009-05-18 Tzu-Chieh Wei