#### Alladi Ramakrishnan Hall

#### Entanglement in light-matter systems

#### Manas Kulkarni

##### ICTS, Bengaluru

*We propose [1, 2] and study the use of photon-mediated interactions for the*

generation of long-range steady-state entanglement between N atoms. Through

the judicious use of coherent drives and the placement of the atoms in a

network of cavity QED systems, a balance between their unitary and

dissipative dynamics can be precisely engineered to stabilize a long-range

correlated state of qubits in the steady state. We discuss the general

theory behind such a scheme and present an example of how it can be used to

drive a register of N atoms to a generalized W state and how the

entanglement can be sustained indefinitely. The achievable steady-state

fidelities for entanglement and its scaling with the number of qubits are

discussed for presently existing superconducting quantum circuits. While the

protocol is primarily discussed for a superconducting circuit architecture,

it is ideally realized in any cavity QED platform that permits controllable

delivery of coherent electromagnetic radiation to specified locations. The

case of N=2 has been recently realized in collaboration with the

experimental group at UC Berkeley [3]

[1] C. D. Aron, M. Kulkarni, H. E. Tureci, Phys. Rev. X 6, 011032 (2016)

[2] C. D. Aron, M. Kulkarni, H. E. Tureci, Phys. Rev. A 90, 062305 (2014)

[3] M.E. Schwartz, L. Martin, E. Flurin, C. Aron, M. Kulkarni, H.E. Tureci,

I. Siddiqi Phys. Rev. Lett. 116, 240503 (2016)

Done