Processing multi-photon state through operation on single photon: methods and applications

TL;DR

This paper introduces methods to convert multi-photon states into single photon qudits, enabling easier manipulation and implementation of quantum logic gates, including multi-control gates like Toffoli, in quantum information processing.

Contribution

It presents novel transformation techniques to map multi-photon states to single photon qudits, simplifying quantum operations and gate constructions.

Findings

Transformation methods enable manipulation of multi-photon states as single photon qudits.

Simplified optical realization of unknown qubit discrimination.

Deterministic multi-control gates, including Toffoli, can be implemented directly.

Abstract

Multi-photon states are widely applied in quantum information technology. By the methods presented in this paper, the structure of a multi-photon state in the form of multiple single photon qubit product can be mapped to a single photon qudit, which could also be in separable product with other photons. This makes the possible manipulation of such multi-photon states in the way of processing single photon states. The optical realization of unknown qubit discrimination [B. He, J. A. Bergou, and Y.-H. Ren, Phys. Rev. A 76, 032301 (2007)] is simplified with the transformation methods. Another application is the construction of quantum logic gates, where the inverse transformations back to the input state spaces are also necessary. We especially show that the modified setups to implement the transformations can realize the deterministic multi-control gates (including Toffoli gate) operating directly on the products of single photon qubits.