Quantum gates utilizing dark and bright states of molecules in dissipative cavities

Alexey Belyanin Texas A&M University

We present a general formalism and specific implementations of quantum gates based on interaction of light with open dissipative nanocavities containing ensembles of molecules. It is well known that many-body eigenstates in an ensemble of two or more quantum emitters are split into bright and dark entangled states with respect to the coupling to a cavity field [1]. While controlling individual molecules buried in a nanocavity is virtually impossible, one can use a whole cavity loaded with quantum emitters as a logical control qubit which interacts with an external incident photon serving as a flying qubit. The degrees of freedom of a photon (e.g., its polarization) are aLected as it scatters or reflects oL of a cavity, or interacts with a cavity while propagating in an evanescently coupled waveguide. This interaction can be controlled by changing the state of the molecules in a cavity with classical electromagnetic fields. In one of many possible implementations sketched in Fig. 1, an initial preparation of the state of molecules by a classical optical pulse controls the polarization state of the reflected photon [2].

[1] M. Tokman et al., Dissipation-driven formation of entangled dark states in strongly-coupled inhomogeneous many- qubit systems in solid-state nanocavities, Phys. Rev. A 107, 013721 (2023).

[2] M. Tokman, J. Verma, and A. Belyanin, Quantum gates utilizing dark and bright states in open dissipative cavity QED, https://arxiv.org/abs/2403.09955.