Thermal amplification and melting of phases in spin–orbit-coupled spin-1 Bose–Einstein condensates

Abstract We implement the Hartree–Fock–Bogoliubov theory with the Popov approximation for a homogeneous Raman-induced spin–orbit-coupled spin-1 Bose–Einstein condensate and investigate the effects of finite temperature ( T ) on the ground-state phase diagram. We calculate the roton gap as a function of Raman coupling (Ω) or quadratic Zeeman field strength ( ε ) to extract the critical points separating the supersolid stripe phase from the plane wave or zero-momentum phase at finite temperatures. We present a few representative finite-temperature phase diagrams for the system in the <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:mi>T</mml:mi> <mml:mo>−</mml:mo> <mml:mi mathvariant="normal">Ω</mml:mi> </mml:mrow> </mml:math> and <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:mi>T</mml:mi> <mml:mo>−</mml:mo> <mml:mi>ϵ</mml:mi> </mml:mrow> </mml:math> planes. Our observations indicate that the supersolid stripe phase melts at finite temperatures. We also discuss the contrasting roles of quantum and thermal fluctuations in shifting the phase boundary separating the supersolid stripe from the plane-wave phase.