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Basic quantum effects are often illustrated using single particle interferences in two-path interferometers. A wider range of non-classical phenomena can be illustrated using three-path interferometers, but the increased complexity of…

Quantum Physics · Physics 2026-02-10 Holger F. Hofmann

Quantum contextuality is a fundamental nonclassical property of quantum systems, regarded as a key resource that demonstrates the computational and informational advantages of quantum over classical systems. Our present work aims to…

Quantum Physics · Physics 2026-03-16 Chang He , Yongjun Wang , Baoshan Wang , Songyi Liu , Yunyi Jia

We show that three unsharp binary qubit measurements are enough to violate a generalized noncontextuality inequality, the LSW inequality, in a state-dependent manner. For the case of trine spin axes we calculate the optimal quantum…

Quantum Physics · Physics 2014-05-15 Ravi Kunjwal , Sibasish Ghosh

Exploring quantum phenomena beyond predictions of any classical model has fundamental importance to understand the boundary of classical and quantum descriptions of nature. As a typical property that a quantum system behaves distinctively…

Since violations of inequalities implied by non-contextual and local hidden variable theories are observed, it is essential to determine the set of (non-)contextual states. Along this direction, one should determine the conditions under…

Quantum Physics · Physics 2023-10-03 Fırat Diker , Zafer Gedik

Fully revealing the mathmatical structure of quantum contextuality is a significant task, while some known contextuality theories are only applicable for rank-1 projectors. That is because they adopt the observable-based definitions. This…

Quantum Physics · Physics 2025-01-17 Songyi Liu , Yongjun Wang , Baoshan Wang , Yunyi Jia

Quantum contextuality plays a significant role in supporting quantum computation and quantum information theory. The key tools for this are the Kochen--Specker and non-Kochen--Specker contextual sets. Traditionally, their representation has…

Quantum Physics · Physics 2025-01-17 Mladen Pavicic

We derive an algebraic framework which identifies the minimal information required to assess how well a quantum device implements a desired quantum operation. Our approach is based on characterizing only the unitary part of an open system's…

Quantum Physics · Physics 2013-10-10 Daniel M. Reich , Giulia Gualdi , Christiane P. Koch

Classical realism demands that system properties exist independently of whether they are measured, while noncontextuality demands that the results of measurements do not depend on what other measurements are performed in conjunction with…

The conflict between classical and quantum physics can be identified through a series of yes-no tests on quantum systems, without it being necessary that these systems be in special quantum states. Kochen-Specker (KS) sets of yes-no tests…

Kochen-Specker (KS) sets are key tools for proving some fundamental results in quantum theory and also have potential applications in quantum information processing. However, so far, their intrinsic complexity has prevented experimentalists…

We show that the phenomenon of quantum contextuality can be used to certify lower bounds on the dimension accessed by the measurement devices. To prove this, we derive bounds for different dimensions and scenarios of the simplest…

Quantum Physics · Physics 2014-06-12 Otfried Gühne , Costantino Budroni , Adan Cabello , Matthias Kleinmann , Jan-Åke Larsson

We find the minimal number of settings to test quantum theory based on real numbers, assuming separability of the sources, modifying the recent proposal [M.-O. Renou et al., Nature 600, 625 (2021)]. The test needs only three settings for…

Quantum Physics · Physics 2022-10-13 Adam Bednorz , Josep Batle

We present a new and feasible test proving quantum contextuality in four-dimensional Hiltbert space. In our scheme, a contradiction between quantum mechanics and noncontextual hidden variables is revealed through the measurement statistics…

Quantum Physics · Physics 2008-06-27 Yoshihiro Nambu

Whereas complementarity manifests itself via two incompatible observables, quantum contextuality can only be revealed via the joint measurements among at least three observables. By incorporating unsharp measurements and joint measurements…

Quantum Physics · Physics 2013-12-24 Sixia Yu , C. H. Oh

The Kochen-Specker theorem states that noncontextual hidden variable models are inconsistent with the quantum predictions for every yes-no question on a qutrit, corresponding to every projector in three dimensions. It has been suggested [D.…

Quantum Physics · Physics 2022-03-16 Adan Cabello , Jan-Åke Larsson

In recent years there has been a growing interest in treating many-body systems as Bell scenarios, where lattice sites play the role of distant parties and only near-neighbor statistics are accessible. We investigate contextuality arising…

Quantum Physics · Physics 2022-07-28 Kaiyan Yang , Xiao Zeng , Yujing Luo , Guowu Yang , Lan Shu , Miguel Navascués , Zizhu Wang

We show that, for any system with a number of levels which can be identified with n qubits, there is an inequality for the correlations between three compatible dichotomic measurements which must be satisfied by any noncontextual theory,…

Quantum Physics · Physics 2010-09-15 Adan Cabello

We show via explicit construction that for six or more parties, there exist extreme rays of the subadditivity cone that can be realized by quantum states, but not by holographic states. This is a counterexample to a conjecture first…

High Energy Physics - Theory · Physics 2024-02-20 Temple He , Veronika E. Hubeny , Massimiliano Rota

Quantum contextuality takes an important place amongst the concepts of quantum computing that bring an advantage over its classical counterpart. For a large class of contextuality proofs, aka. observable-based proofs of the Kochen-Specker…