



01437nas a2200157   4500008004100000245003500041210003300076260001500109300001100124490000700135520104900142100001501191700001701206700001901223856003701242       2015                        eng d00aA chemical potential for light0 achemical potential for light  c2014/05/22  a1743050 v923 aPhotons are not conserved in interactions with other matter. Consequently, when understanding the equation of state and thermodynamics of photons, while we have a concept of temperature for energy conservation, there is no equivalent chemical potential for particle number conservation. However, the notion of a chemical potential is crucial in understanding a wide variety of single- and many-body effects, from transport in conductors and semi-conductors to phase transitions in electronic and atomic systems. Here we show how a direct modification of the system-bath coupling via parametric oscillation creates an effective chemical potential for photons even in the thermodynamic limit. Specific implementations, using circuit-QED or optomechanics, are feasible using current technologies, and we show a detailed example demonstrating the emergence of Mott Insulator-superfluid transition in a lattice of nonlinear oscillators. Our approach paves the way for quantum simulation, quantum sources and even electron-like circuits with light.
1 aHafezi, M.1 aAdhikari, P.1 aTaylor, J., M.  uhttp://arxiv.org/abs/1405.5821v2