Quantum 10, 2084 (2026). https://doi.org/10.22331/q-2026-04-28-2084 The question of “non-locality of a single photon”, which started with a paper by Tan, Walls and Collett (TWC, 1991) stirred a thirty years long debate. This hampered attempts to […]
Tag: quantumjournal
Quantum 10, 2083 (2026). https://doi.org/10.22331/q-2026-04-24-2083 Quantum information is fragile and must be protected by a quantum error-correcting code for large-scale practical applications. Recently, highly efficient quantum codes have been discovered which require a high degree […]
Quantum 10, 2082 (2026). https://doi.org/10.22331/q-2026-04-23-2082 We present a formalism that allows for the direct manipulation and optimization of subspaces, circumventing the need to optimize individual states when using subspace methods. Using the determinant state mapping, […]
Quantum 10, 2081 (2026). https://doi.org/10.22331/q-2026-04-23-2081 Waveguide quantum electrodynamics (QED) provides a powerful framework for engineering quantum interactions, traditionally relying on periodic photonic arrays with continuous energy bands. Here, we investigate waveguide QED in a fundamentally […]
Quantum 10, 2080 (2026). https://doi.org/10.22331/q-2026-04-23-2080 Holonomic quantum computation exploits the geometric evolution of eigenspaces of a degenerate Hamiltonian to implement unitary evolution of computational states. In this work we introduce a framework for performing scalable […]
Quantum 10, 2079 (2026). https://doi.org/10.22331/q-2026-04-21-2079 We introduce parallel-sequential (PS) circuits, a family of quantum circuit layouts that interpolate between brickwall and sequential circuits, which introduces control parameters governing a trade-off between the amount of entanglement […]
Quantum 10, 2078 (2026). https://doi.org/10.22331/q-2026-04-21-2078 We discuss the estimation of the distance of a given mixed many-body quantum state to the set of fully separable states, applied to the concrete scenario of collective spin states. […]
Quantum 10, 2077 (2026). https://doi.org/10.22331/q-2026-04-21-2077 In this work we present a hierarchy of generalized contextuality. It refines the traditional binary distinction between contextual and noncontextual theories, and facilitates their comparison based on how contextual they […]
Quantum 10, 2076 (2026). https://doi.org/10.22331/q-2026-04-21-2076 Many practically important NP-hard optimization problems are inherently higher-order polynomial optimizations, which are typically addressed using approximation algorithms. Classical relaxations express polynomial objectives over a polynomial basis and solve the […]
Quantum 10, 2075 (2026). https://doi.org/10.22331/q-2026-04-21-2075 In this paper, we investigate three schemes for implementing Controlled-Z (CZ) gates between individual ytterbium (Yb) rare-earth ions doped into yttrium orthovanadate (YVO$_4$ or YVO). Specifically, we investigate the CZ […]
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