We focus on the information theoretic study of quantifying the information content in the outcome of a quantum measurement, also referred to as the measurement compression problem (MCP). The goal of this work is to develop a unified framework of tools to address this problem in diverse network scenarios both in the one-shot and asymptotic regimes. Designing a new measurement simulation protocol based on likelihood POVMs and developing analysis techniques based on a proxy state, we present a unified framework to derive the current known largest inner bounds for several network scenarios. Our findings include new one-shot inner bounds for the distributed MCP with and without quantum side information and the distributed quantum classical rate distortion problems.
We focus on the information theoretic study of quantifying the information content in the outcome of a quantum measurement, also referred to as the measurement compression problem (MCP). The goal of this work is to develop a unified framework of tools to address this problem in diverse network scenarios both in the one-shot and asymptotic regimes. Designing a new measurement simulation protocol based on likelihood POVMs and developing analysis techniques based on a proxy state, we present a unified framework to derive the current known largest inner bounds for several network scenarios. Our findings include new one-shot inner bounds for the distributed MCP with and without quantum side information and the distributed quantum classical rate distortion problems.
By developing a new framework of likelihood POVMs, analysis techniques and a new proof of the quantum covering lemma, we address the simulation of separable quantum measurement over bipartite states. In addition to a new one shot inner bound that naturally generalizes to the asymptotic case, we demonstrate the power, generality and universality of the developed techniques in the most general distributed measurement scenario by recovering all current known inner bounds. In addition to the above results, this framework is appealing in being the most natural and simple POVM simulation protocol.
Three distributed parties, two transmitters (Txs) and a receiver (Rx), hold one component each of a tripartite quantum state ρA1A2C. The goal is to simulate the action of a separable instrument acting on the A1 and A2 components, with the Rx recovering the classical outcome. To enable this, each Tx k can transfer bits on a noiseless bit pipe and share randomness at rates Rk and Ck, respectively, with the Rx. Undertaking a Shannon-theoretic study, we characterize two new sets of inner bounds. The first set, derived for the one-shot regime, is based on instrument simulation protocols built using unstructured IID codes, while the second set, derived for the asymptotic regime, relies on coset codes and new decoding POVMs. The first set of bounds recovers current known inner bounds for instrument and measurement simulation in all previously studied scenarios. Our protocols are based on likelihood POVMs, and our analysis leverages Sen's smooth multiparty covering and simultaneous decoding, while handling the distributed-component scenario via a compatible operator sliding trick.
We consider the task of faithfully simulating a quantum measurement, acting on a joint bipartite quantum state, in a distributed manner. In this setup, the constituent sub-systems of the joint quantum state are measured by two agents, Alice and Bob. A third agent, Charlie, receives the measurement outcomes sent by Alice and Bob. Charlie uses local and pairwise shared randomness to compute a bivariate function of the measurement outcomes. The objective of three agents is to faithfully simulate the given distributed quantum measurement acting on the given quantum state while minimizing the communication and shared randomness rates. We demonstrate a new inner bound to the rate region using random structured POVMs based on asymptotically good algebraic codes, and characterize the performance limit using single-letter quantum mutual information quantities. This new bound subsumes the largest known inner bound and improves upon it strictly for identified examples. One of the challenges in analyzing these structured POVMs is that they exhibit only pairwise independence and induce only uniform single-letter distributions. We address these in the non-commutative quantum setting, and provide a two-party distributed faithful simulation and function computation protocol.
This paper concerns the problem of quantum measurement compression with side information in the one-shot setting with shared-randomness. In this problem, Alice shares a pure quantum state with Bob and the reference system. She performs a measurement on her registers and wishes to communicate the outcome to Bob using shared-randomness and classical communication. The outcome that Bob receives must be correctly correlated with the reference system and his own registers. Our goal is to concurrently minimize the classical communication and shared-randomness cost. The suggested protocol presented in this paper is based on convex-split and position based decoding. The communication is upper bounded in terms of smooth max and hypothesis testing relative entropies. A second protocol addresses the task of strong randomness extraction in the presence of quantum side information. The protocol provides an error guarantee in terms of relative entropy (as opposed to trace distance) and extracts close to the optimal number of uniform bits. As an application, we provide a new achievability result for the task of quantum measurement compression without feedback, in which Alice does not need to know the outcome of the measurement. The result achieves the optimal number of bits communicated and the required number of bits of shared-randomness, for the same task in the asymptotic and i.i.d. setting.
We consider the task of faithfully simulating a distributed quantum measurement, wherein we provide a protocol for the three parties, Alice, Bob and Charlie, to simulate a repeated action of a distributed quantum measurement using a pair of non-product approximating measurements by Alice and Bob, followed by a stochastic mapping at Charlie. The objective of the protocol is to utilize minimum resources, in terms of classical bits needed by Alice and Bob to communicate their measurement outcomes to Charlie, and the common randomness shared among the three parties, while faithfully simulating independent repeated instances of the original measurement. To achieve this, we develop a mutual covering lemma and a technique for random binning of distributed quantum measurements, and, in turn, characterize a set of sufficient communication and common randomness rates required for asymptotic simulatability in terms of single-letter quantum information quantities. In the special case, where the Charlie’s action is restricted to a deterministic mapping, we develop a one-shot performance characterization of the distributed faithful simulation problem. Furthermore, using these results we address a distributed quantum rate-distortion problem, where we characterize the achievable rate distortion region through a single-letter inner bound. Finally, via a technique of single-letterization of multi-letter quantum information quantities, we provide an outer bound for the rate-distortion region.
This paper is eligible for the Jack Reil Wolf ISIT Student Paper Award.We prove new one shot achievability results for measurement compression of quantum instruments with side information at the receiver. Unlike previous one shot results for this problem, our one shot bounds are nearly optimal and do not need catalytic randomness. In fact, we state a more general problem called centralised multi link measurement compression with quantum side information and provide one shot achievability results for it. As a simple corollary, we obtain one shot measurement compression results for quantum instruments with side information that we mentioned earlier. All our one shot results lead to the standard results for this problem in the asymptotic iid setting. We prove our achievability bounds by first proving a novel sequential classical quantum multipartite covering lemma, which should be of independent interest.