Ultrafast entangling gates between nuclear spins using photo-excited triplet states

TL;DR

This paper demonstrates ultrafast entangling gates between nuclear spins using a transient electron spin from photo-excited triplet states, significantly speeding up quantum operations and reducing decoherence.

Contribution

It introduces a method to perform rapid entangling gates between nuclear spins via transient electron spins from photo-excited triplet states, enabling faster quantum control.

Findings

Entangling gates performed in hundreds of nanoseconds

Speed increase of five orders of magnitude over liquid-state J coupling

Potential for application in systems like NV centers

Abstract

The representation of information within the spins of electrons and nuclei has been powerful in the ongoing development of quantum computers. Although nuclear spins are advantageous as quantum bits (qubits) due to their long coherence lifetimes (exceeding seconds), they exhibit very slow spin interactions and have weak polarisation. A coupled electron spin can be used to polarise the nuclear spin and create fast single-qubit gates, however, the permanent presence of electron spins is a source of nuclear decoherence. Here we show how a transient electron spin, arising from the optically excited triplet state of C60, can be used to hyperpolarise, manipulate and measure two nearby nuclear spins. Implementing a scheme which uses the spinor nature of the electron, we performed an entangling gate in hundreds of nanoseconds: five orders of magnitude faster than the liquid-state J coupling. This approach can be widely applied to systems comprising an electron spin coupled to multiple nuclear spins, such as NV centres, while the successful use of a transient electron spin motivates the design of new molecules able to exploit photo-excited triplet states.