Deterministic local doubling of W states

Abstract

In large quantum systems multipartite entanglement can be found in many inequivalent classes under local operations and classical communication. Preparing states of arbitrary size in different classes is important for performing a wide range of quantum protocols. W states, in particular, constitute a class with a variety of quantum networking protocols. However, all known schemes for preparing W states are probabilistic, with resource requirements increasing at least sub-exponentially. We propose a deterministic scheme for preparing W states that requires no prior entanglement and can be performed locally. We introduce an all-optical setup that can efficiently prepare W states of arbitrary size. Our scheme advances the use of W states in real-world quantum networks and could be extended to other physical systems.

Efficient Quantum Algorithms for GHZ and W States, and Implementation on the IBM Quantum Computer

“…In the special case , our scheme is essentially equivalent to the proposal of ref. [] (and references therein). However for , ref.…”

“…However for , ref. [] uses random processes (polarization‐dependent losses and projective measurements) to suppress or add quantum bits, and unfortunately the success probability diminishes drastically as one moves away from powers of two. Let us also mention the special case on ref.…”

“…In the present paper, we concentrate on and which are two typical representatives of the general multipartite entangled jungle. They also constitute very interesting and powerful targets as fundamental resources in distributed quantum information processing (see also the book reviews GHZN and are completely different: the former are fragile against loss and important for example in quantum secret sharing, while the latter are robust against loss and central to quantum memories, multiparty quantum network protocols, and universal quantum cloning machines.…”

“…Many schemes have been designed to produce these states for large N (see, e.g., ref. []), but it is also important to consider other aspects like probabilistic versus deterministic creation, possibility to extend them locally in quantum networks, or to transform them non‐locally . In this work, we focus on deterministic computationally efficient schemes producing these states.…”

Remote preparation of W states from imperfect bipartite sources

“…In contrast, the authors of Ref. [27] propose a deterministic scheme to create four-partite W states, which can be extended to generate W states of arbitrary dimension [28]. More recently, a procedure was suggested to create entangled states of several degrees of freedom, which is particularly suited for W states.…”