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Finding exponential separation between quantum and classical information tasks is like striking gold in quantum information research. Such an advantage is believed to hold for quantum computing but is proven for quantum communication…

We propose a novel approach to qubit thermometry using a quantum switch, that introduces an indefinite causal order in the probe-bath interaction, to significantly enhance the thermometric precision. The resulting qubit probe shows improved…

Quantum Physics · Physics 2018-12-19 Chiranjib Mukhopadhyay , Manish K. Gupta , Arun Kumar Pati

A generic qubit unitary operator affected by depolarizing noise is duplicated and inserted in a quantum switch process realizing a superposition of causal orders. The characterization of the resulting switched quantum channel is worked out…

Quantum Physics · Physics 2021-04-14 Francois Chapeau-Blondeau

In quantum mechanics events can happen in no definite causal order: in practice this can be verified by measuring a causal witness, in the same way that an entanglement witness verifies entanglement. Indefinite causal order can be observed…

Quantum Physics · Physics 2018-11-05 K. Goswami , C. Giarmatzi , M. Kewming , F. Costa , C. Branciard , J. Romero , A. G. White

For minimum-error channel discrimination tasks that involve only unitary channels, we show that sequential strategies may outperform the parallel ones. Additionally, we show that general strategies that involve indefinite causal order are…

Quantum Physics · Physics 2022-05-16 Jessica Bavaresco , Mio Murao , Marco Túlio Quintino

Via nonlocality distillation, a number of copies of a given nonlocal correlation can be turned into a new correlation displaying a higher degree of nonlocality. Apart from its clear relevance in situations where nonlocality is a resource,…

Quantum Physics · Physics 2019-07-10 S. G. A. Brito , M. G. M. Moreno , A. Rai , R. Chaves

Quantum coherence in a qubit is vulnerable to environmental noise. When long quantum calculation is run on a quantum processor without error correction, the noise often causes fatal errors and messes up the calculation. Here, we propose…

Quantum Non-Gaussian states are considered as a useful resource for many tasks in quantum information processing, from quantum metrology and quantum sensing to quantum communication and quantum key distribution. Another useful tool that is…

Quantum Physics · Physics 2021-08-31 Seid Koudia , Abdelhakim Gharbi

Virtual distillation is an error-mitigation technique that reduces quantum-computation errors without assuming the noise type. In scenarios where the user of a quantum circuit is required to additionally employ peripherals, such as delay…

Quantum Physics · Physics 2023-07-04 Yong Siah Teo , Seongwook Shin , Hyukgun Kwon , Seok-Hyung Lee , Hyunseok Jeong

Production of quantum states exhibiting a high degree of entanglement out of noisy conditions is one of the main goals of quantum information science. Here, we provide a conditional yet efficient entanglement distillation method which…

Quantum theory puts forward phenomena unexplainable by classical physics - or information, for that matter. A prominent example is non-locality. Non-local correlations cannot be explained, in classical terms, by shared information but only…

Quantum Physics · Physics 2014-08-26 Helen Ebbe , Stefan Wolf

We present an optimal probabilistic protocol to distill quantum coherence. Inspired by a specific entanglement distillation protocol, our main result yields a strictly incoherent operation that produces one of a family of maximally coherent…

Quantum Physics · Physics 2019-01-23 Gokhan Torun , Ludovico Lami , Gerardo Adesso , Ali Yildiz

Entanglement distillation is a key primitive for distributing high-quality entanglement between remote locations. Probabilistic noiseless linear amplification based on the quantum scissors is a candidate for entanglement distillation from…

Quantum Physics · Physics 2019-08-15 Kaushik P. Seshadreesan , Hari Krovi , Saikat Guha

Bidirectional devices are devices for which the roles of the input and output ports can be exchanged. Mathematically, these devices are described by bistochastic quantum channels, namely completely positive linear maps that are both…

Quantum Physics · Physics 2026-02-03 Luca Apadula , Alessandro Bisio , Giulio Chiribella , Paolo Perinotti , Kyrylo Simonov

We demonstrate non-classical cooling on the IBMq cloud quantum computer. We implement a recently proposed refrigeration protocol which relies upon indefinite causal order for its quantum advantage. We use quantum channels which, when used…

Quantum Physics · Physics 2021-11-29 David Felce , Vlatko Vedral , Felix Tennie

We propose a thermodynamic refrigeration cycle which uses Indefinite Causal Orders to achieve non-classical cooling. The cycle cools a cold reservoir while consuming purity in a control qubit. We first show that the application to an input…

Quantum Physics · Physics 2021-11-29 David Felce , Vlatko Vedral

Quantum key distribution promises information-theoretically secure communication, with data post-processing playing a vital role in extracting secure keys from raw data. While hardware advancements have significantly improved practical…

Quantum Physics · Physics 2025-12-01 Zhenyu Du , Guoding Liu , Xingjian Zhang , Xiongfeng Ma

Recent studies have shown that quantum information may be effectively transmitted by a finite collection of completely depolarizing channels in a coherent superposition of different orders, via an operation known as the quantum $\tt…

Quantum Physics · Physics 2024-07-04 Zhen Wu , James Fullwood , Zhihao Ma , Siqi Zhou , Qi Zhao , Giulio Chiribella

Probabilistic quantum filtering is proposed to properly adapt sequential independent quantum channels in order to stop sudden death of entanglement. In the adaptation, the quantum filtering does not distill or purify more entanglement, it…

Quantum Physics · Physics 2009-05-07 Miroslav Gavenda , Radim Filip

Quantum network states are multipartite states built from distributing pairwise entanglement among parties and underpin the paradigm of quantum networks for quantum information processing. In this work we introduce the problem of partial…

Quantum Physics · Physics 2025-09-30 Aitor Balmaseda , Julio I. de Vicente