Hatim Salih et al, ‘Exchange-free computation on an unknown qubit at a distance’, 2021 New J. Phys. 23 013004. DOI: https://doi.org/10.1088/1367-2630/abd3c4
We present a way of directly manipulating an arbitrary qubit, without the exchange of any particles. This includes as an application the exchange-free preparation of an arbitrary quantum state at Alice by a remote classical Bob. As a result, we are able to propose a protocol that allows one party to directly enact, by means of a suitable program, any computation exchange-free on a remote second party’s unknown qubit. Further, we show how to use this for the exchange-free control of a universal two-qubit gate, thus opening the possibility of directly enacting any desired algorithm remotely on a programmable quantum circuit.
