The realization of equilibrium superradiant quantum phases (photon condensates) in a spatially uniform quantum cavity field is forbidden by a "no-go"theorem stemming from gauge invariance. We here show that the no-go theorem does not apply to spatially varying quantum cavity fields. We find a criterion for its occurrence that depends solely on the static, nonlocal orbital magnetic susceptibility χorb(q), of the electronic system (ES) evaluated at a cavity photon momentum ℏq. Only 3DESs satisfying the Condon inequality χorb(q)>1/(4π) can harbor photon condensation. For the experimentally relevant case of two-dimensional (2D) ESs embedded in quasi-2D cavities the criterion again involves χorb(q) but also the vertical size of the cavity. We use these considerations to identify electronic properties that are ideal for photon condensation. Our theory is nonperturbative in the strength of electron-electron interaction and therefore applicable to strongly correlated ESs.

Theory of photon condensation in a spatially varying electromagnetic field

Andolina G. M.;Pellegrino F. M. D.;Giovannetti V.;Polini M.
2020

Abstract

The realization of equilibrium superradiant quantum phases (photon condensates) in a spatially uniform quantum cavity field is forbidden by a "no-go"theorem stemming from gauge invariance. We here show that the no-go theorem does not apply to spatially varying quantum cavity fields. We find a criterion for its occurrence that depends solely on the static, nonlocal orbital magnetic susceptibility χorb(q), of the electronic system (ES) evaluated at a cavity photon momentum ℏq. Only 3DESs satisfying the Condon inequality χorb(q)>1/(4π) can harbor photon condensation. For the experimentally relevant case of two-dimensional (2D) ESs embedded in quasi-2D cavities the criterion again involves χorb(q) but also the vertical size of the cavity. We use these considerations to identify electronic properties that are ideal for photon condensation. Our theory is nonperturbative in the strength of electron-electron interaction and therefore applicable to strongly correlated ESs.
2020
Settore FIS/03 - Fisica della Materia
File in questo prodotto:
File Dimensione Formato  
2005.09088.pdf

accesso aperto

Tipologia: Accepted version (post-print)
Licenza: Solo Lettura
Dimensione 444.18 kB
Formato Adobe PDF
444.18 kB Adobe PDF
PhysRevB.102.125137.pdf

accesso aperto

Tipologia: Published version
Licenza: Solo Lettura
Dimensione 458.35 kB
Formato Adobe PDF
458.35 kB Adobe PDF

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11384/101048
Citazioni
  • ???jsp.display-item.citation.pmc??? ND
  • Scopus 55
  • ???jsp.display-item.citation.isi??? 53
social impact