Band-inverted electron-hole bilayers support quantum spin Hall insulator and excitoncondensate phases. Interest in quantum spin Hall effect in these systems has recently putthem in the spotlight. We investigate such a bilayer in an external magnetic field. We showthat the interlayer correlations lead to formation of a helical quantum Hall exciton condensatestate. Existence of the counterpropagating edge modes in this system results in formation ofa ground state spin-texture not supporting gapless single-particle excitations. The chargededge excitations in a sufficiently narrow Hall bar are confined: a charge on one of the edgesalways gives rise to an opposite charge on the other edge. Magnetic field and gate voltagesallow the control of a confinement-deconfinement transition of charged edge excitations,which can be probed with nonlocal conductance. Confinement-deconfinement transitions areof great interest, not least because of their possible significance in shedding light on theconfinement problem of quarks.
展开▼
