Deterministic local doubling of W states

Abstract

In large quantum systems, multipartite entanglement can be found in many inequivalent classes. Preparing states of arbitrary size in different classes is important for performing a wide range of quantum protocols.W" role="presentation" style="display: inline; font-size: 12.88px; line-height: normal; word-spacing: normal; overflow-wrap: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; padding: 0px; margin: 0px; position: relative;">𝑊Wstates, in particular, constitute a class with a variety of quantum networking protocols. However, all known schemes for preparing polarization encoded photonicW" role="presentation" style="display: inline; font-size: 12.88px; line-height: normal; word-spacing: normal; overflow-wrap: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; padding: 0px; margin: 0px; position: relative;">𝑊Wstates are probabilistic, with resource requirements increasing at least sub-exponentially. We propose a deterministic scheme for preparingW" role="presentation" style="display: inline; font-size: 12.88px; line-height: normal; word-spacing: normal; overflow-wrap: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; padding: 0px; margin: 0px; position: relative;">𝑊Wstates of size of any power of 2, which requires no prior entanglement and can be performed locally. We introduce an all-optical setup that can efficiently double the size ofW" role="presentation" style="display: inline; font-size: 12.88px; line-height: normal; word-spacing: normal; overflow-wrap: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; padding: 0px; margin: 0px; position: relative;">𝑊Wstates of arbitrary size. Our scheme advances the use ofW" role="presentation" style="display: inline; font-size: 12.88px; line-height: normal; word-spacing: normal; overflow-wrap: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; padding: 0px; margin: 0px; position: relative;">𝑊Wstates in real-world quantum networks and could be extended to other physical systems.