Polar Phase of 1D Bosons with Large Spin

Abstract

Spinor ultracold gases in one dimension represent an interesting example of strongly correlated quantum fluids. They have a rich phase diagram and exhibit a variety of quantum phase transitions. We consider a one-dimensional spinor gas of bosons with a large spin $S$. A particular example is the gas of chromium atoms (S=3), where the dipolar collisions efficiently change the magnetization and make the system sensitive to the linear Zeeman effect. We argue that in one dimension the most interesting effects come from the pairing interaction. If this interaction is negative, it gives rise to a (quasi)condensate of singlet bosonic pairs with an algebraic order at zero temperature, and for $(2S+1)\gg 1$ the saddle point approximation leads to physically transparent results. Since in one dimension one needs a finite energy to destroy a pair, the spectrum of spin excitations has a gap. Hence, in the absence of magnetic field there is only one gapless mode corresponding to phase fluctuations of the pair quasicondensate. Once the magnetic field exceeds the gap another condensate emerges, namely the quasicondensate of unpaired bosons with spins aligned along the magnetic field. The spectrum then contains two gapless modes corresponding to the singlet-paired and spin-aligned unpaired bose-condensed particles, respectively. At T=0 the corresponding phase transition is of the commensurate-incommensurate type.

17 pages, 5 figures; references added, conclusions section is modified

References in corpus (11)

• Strong dipolar effects in a quantum ferrofluid
• Stabilizing a purely dipolar quantum gas against collapse
• Spontaneously modulated spin textures in a dipolar spinor Bose-Einstein condensate
• Phase diagram of spin-1 bosons on one-dimensional lattices
• Broken axisymmetry phase of a spin-1 ferromagnetic Bose-Einstein condensate
• Control of dipolar relaxation in external fields
• Coherent collapse of a dipolar Bose-Einstein condensate for different trap geometries
• Spin relaxation and band excitation of a dipolar BEC in 2D optical lattices
• Thermodynamics of a Bose Einstein condensate with free magnetization
• Mott-insulator phases of spin-3/2 fermions in the presence of quadratic Zeeman coupling
• On the spin-liquid phase of one dimensional spin-1 bosons

Cited by in corpus (10)

• Fermi gases in one dimension: From Bethe Ansatz to experiments
• Strongly Correlated Quantum Fluids: Ultracold Quantum Gases, Quantum Chromodynamic Plasmas, and Holographic Duality
• Dipolar and spinor bosonic systems
• Exciton transport in a germanium quantum dot ladder
• Critical phenomena in one dimension from a Bethe ansatz perspective
• Dipolar atomic spin ensembles in a double-well potential
• Quantum criticality of spin-1 bosons in a 1D harmonic trap
• Universality class of quantum criticality for strongly repulsive spin-1 bosons with antiferromagnetic spin-exchange interaction
• Quantum Criticality of one-dimensional multicomponent Fermi Gas with Strongly Attractive Interaction
• Spinor Bose gas in an elongated trap