Exciton-Polariton Condensate — Lower Branch
Strong coupling between cavity photons and quantum-well excitons creates polariton quasiparticles
Bare photon E
ph
(k)
Bare exciton E
X
Lower polariton branch (LP)
Upper polariton branch (UP)
Condensate occupancy n(k)
Coupling Parameters
Rabi splitting 2Ω (meV):
10
Detuning δ = E
cav
−E
X
(meV):
0
Exciton energy E
X
(eV):
1.60
Condensate
Pump power (× threshold):
2.0
Blueshift g·n (meV):
3
LP linewidth γ (meV):
0.5
Theory
LP: E
LP
= ½(E
X
+E
ph
) − ½√(δ²+Ω²)
UP: E
UP
= ½(E
X
+E
ph
) + ½√(δ²+Ω²)
Photon dispersion:
E
ph
(k) = E
cav
+ ℏ²k²/2m
ph
Hopfield coeff |C
k
|² = photon fraction
Condensate blueshifts LP by g·n
Threshold: gain = loss