Simultaneous sorting many quDits using different input ports

TL;DR

This paper defines a general quantum sorter for multi-level systems, proves the impossibility of perfect multi-particle sorting without state alteration, and proposes an approximate, high-speed sorting method that reveals initial state information through detector clicks.

Contribution

It introduces a formal definition of multi-port quantum sorters, proves their fundamental limitations, and offers an approximate solution suitable for high-speed quantum information processing.

Findings

Perfect multi-particle quantum sorter is impossible.

Proposed an approximate sorter that changes final states.

The method reveals initial states via detector click statistics.

Abstract

Quantum sorter has gained a lot of attention during the last years due to its wide application in quantum information processing and quantum technologies. A challenging task is the construction of a quantum sorter, which collect many high-dimensional quantum systems, which are simultaneously incident on different input ports of the device. In this paper we give the definition of the general quantum sorter of multi-level quantum systems. We prove the impossibility of the construction of the perfect quantum sorter, which works for many particles incident on any input port, while keeping their states unmodified. Further we propose an approximate multi-particle multi-input-port quantum sorter, which performs the selection of the particles in a certain output port according to the properties of the initial states, but changing the final states. This method is useful for those situations which require high speed of quantum state sorting. Thus, the information contained in the initial states of the particles is revealed by the click statistics of the detectors situated in each output port.