Events in Physics
Gunnar Moeller, Cambridge
Location: PS1.28
The physics of the Quantum Hall bilayer systems at filling fractions near \nu=1/2+1/2 is marked by a transition from a compressible phase with strong intralayer correlation to an incompressible phase with strong interlayer correlations as the layer separation d is reduced below some critical value.? Deep in the intralayer phase (large separation) the system can be interpreted as a fluid of composite fermions (CFs), whereas deep in the interlayer phase (small separation) the system can be interpreted as a fluid of composite bosons (CBs).
We present evidence for a phase with interlayer pairing occurring for d \gtrsim \ell_0 , which is continuously connected to the CF liquid at large layer separation [1]. Our understanding of this phase derives from the formulation of trial wavefunctions for the ground-state of the quantum Hall bilayer, relying on the comparison to exact results for small systems. We find that p-wave paired CF wavefunctions provide an exceedingly good description of the ground-state for d \gtrsim \ell_0 with \ell_0 the magnetic length. To capture the physics at smaller layer separation, we generalize the reasoning of [2] and introduce the idea of modified pairing wavefunctions by allowing the CFs to be replaced continuously by CBs [3]. Thus, we construct exceedingly good wavefunctions for interlayer spacings of d \lesssim \ell_0, also. The accuracy of the wavefunctions discussed here, compared with exact diagonalization, approaches that of the celebrated Laughlin wavefunction.
We present evidence for a phase with interlayer pairing occurring for d \gtrsim \ell_0 , which is continuously connected to the CF liquid at large layer separation [1]. Our understanding of this phase derives from the formulation of trial wavefunctions for the ground-state of the quantum Hall bilayer, relying on the comparison to exact results for small systems. We find that p-wave paired CF wavefunctions provide an exceedingly good description of the ground-state for d \gtrsim \ell_0 with \ell_0 the magnetic length. To capture the physics at smaller layer separation, we generalize the reasoning of [2] and introduce the idea of modified pairing wavefunctions by allowing the CFs to be replaced continuously by CBs [3]. Thus, we construct exceedingly good wavefunctions for interlayer spacings of d \lesssim \ell_0, also. The accuracy of the wavefunctions discussed here, compared with exact diagonalization, approaches that of the celebrated Laughlin wavefunction.