Constraining the state space in any physical theory with the principle of information symmetry

Banik, Manik; Saha, Sutapa; Guha, Tamal; Agrawal, Sristy; Bhattacharya, Some Sankar; Roy, Arup; Majumdar, A. S.

doi:10.1103/physreva.100.060101

Cited by 12 publications

(5 citation statements)

References 53 publications

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“…For instance, classical information encoded in non-orthogonal quantum states, either pure or mixed, cannot be perfectly decoded since the nocloning theorem [9] ( more generally the no-broadcasting theorem [10]) puts restriction on their perfect discrimination. Such a constraint is strictly quantum (more precisely, non-classical [11,12]) in nature as pure classical states are always perfectly distinguishable [13]. While a set of mutually orthogonal quantum states can always be perfectly distinguished, interesting situations arise for multipartite quantum systems when discriminating operations among the spatially separated parties holding different subsystems are limited to local quantum operation assisted with classical communication (LOCC).…”

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confidence: 99%

Local Quantum State Marking

Sen,

Lobo,

Naik

et al. 2021

Preprint

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We introduce the task of local state marking (LSM), where some multipartite quantum states chosen randomly from a known set of states are distributed among spatially separated parties without revealing the identities of the individual states. The collaborative aim of the parties is to correctly mark the identities of states under the restriction that they can perform only local quantum operations (LO) on their respective subsystems and can communicate with each other classically (CC) -popularly known as the operational paradigm of LOCC. While mutually orthogonal states can always be marked exactly under global operations, we show that this is not the case under LOCC in general. We establish that the LSM task is distinct from the task of local state distinguishability (LSD)perfect LSD always implies perfect LSM, whereas we show that the converse does not hold in general. We also explore entanglement assisted marking of states that are otherwise locally unmarkable and report intriguing entanglement assisted catalytic LSM phenomenon.

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confidence: 99%

Local Quantum State Marking

Sen,

Lobo,

Naik

et al. 2021

Preprint

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“…The generalized probability theory (GPT) framework admits a broader mathematical setup that includes quantum and classical theory as special examples. It can incorporate the notion of indistinguishable pure states without invoking the much constrained Hilbert space structure of quantum mechanics [26]. Here we show that this general framework can also exhibit a nonzero gap in optimal success probabilities of product states discrimination under local and global protocols, i.e., it evinces the NWE phenomenon.…”

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confidence: 86%

Nonlocality without entanglement: Quantum theory and beyond

Bhattacharya

Saha

Guha

et al. 2020

Phys. Rev. Research

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Quantum nonlocality without entanglement (Q-NWE) captures nonlocal behavior of multipartite product states as they may entail global operation for optimal decoding of the classical information encoded in the state ensemble that allows local preparation. In this Rapid Communication we show that the phenomena of NWE is not specific to quantum theory only, but rather a class of generalized probabilistic theories that can exhibit such behavior. In fact, several manifestations of NWE, e.g., asymmetric local discrimination, suboptimal local discrimination, the notion of separable but locally unimplementable measurements arise generically in operational theories other than quantum theory. We propose a framework to compare the strength of NWE in different theories and show that such behavior in quantum theory is limited, suggesting a specific topological feature of quantum theory, namely, the continuity of state space structure. Our work adds the erstwhile missing foundational appeal to the study of NWE phenomena along with its information-theoretic relevance.

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“…Even gon different non-classical aspects of these models which in turn provide better understandings of the Hilbert space structure of quantum theory [81][82][83][84][85][86]. Here we study these models to explore their communication utility while playing the Restaurant games.…”

Section: Odd Gonmentioning

confidence: 99%

Classical analogue of quantum superdense coding and communication advantage of a single quantum

Patra¹,

Naik²,

Lobo³

et al. 2022

Preprint

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We analyze the communication utility of a single quantum system when the sender and receiver share neither any entanglement nor any classical shared randomness. To this aim, we propose a class of two-party communication games that cannot be won with a noiseless 1-bit classical channel, whereas the goal can be perfectly achieved if the channel is assisted by classical shared randomness. This resembles an advantage similar to the quantum superdense coding phenomenon where preshared entanglement can enhance communication utility of a perfect quantum communication line. Quite surprisingly, we show that a qubit communication without any assistance of classical shared randomness can achieve the goal, and hence establishes a novel quantum advantage in the simplest communication scenario. In pursuit of a deeper origin of this advantage we show that an advantageous quantum strategy must invoke quantum interference both at the encoding step by the sender and at the decoding step by the receiver. A subclass of these games can be won deterministically if the sender communicates some non-classical toy systems described by symmetric polygonal state spaces. We then proceed to design a variant of the game that can be won neither with 1-bit communication nor with a polygon system, but 1-qubit communication yields a perfect strategy, establishing a strict quantum nature of the advantage. To this end, we show that the quantum advantages are robust against imperfect encodings-decodings, making the protocols implementable with presently available quantum technologies.

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Constraining the state space in any physical theory with the principle of information symmetry

Cited by 12 publications

References 53 publications

Local Quantum State Marking

Local Quantum State Marking

Nonlocality without entanglement: Quantum theory and beyond

Classical analogue of quantum superdense coding and communication advantage of a single quantum

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