Scientists / Open questions

Bertrand I. Halperin

Condensed matter theory; critical phenomena; quantum Hall effect

13 questions

Boundaries of validity of dislocation-mediated melting in two dimensions: first-order versus two-stage scenarios, substrate-coupled renormalization-group flows, and quantitative control of the theory's approximations
Finite-temperature theory of spin transport through antiferromagnetic insulators: two-fluid dynamics of the magnon condensate and thermal cloud, and its experimental identification
Unresolved phase-diagram questions of the Nelson–Halperin model of a smectic layer with tilted molecules: order of symmetry-equivalent transitions, the strong-coupling fate of the unlocked tilted hexatic, and the stacking of coupled layers
Microscopic theory of the cyclotron-resonance line shape of an interacting, disordered two-dimensional electron gas beyond the leading-order, integer-filling, strong-field limit, and the origin of anomalous cyclotron-resonance splittings at intermediate magnetic fields
Quantitative theory and experimental realization of spin-diffusion-mediated nonlocal charge transport with k-linear spin-orbit coupling in the spin Hall effect regime
Realizing the parity-based diagnostics of the non-Abelian $\nu=5/2$ quantum Hall state in realistic devices: quasiparticle-parity control, capacitance, stability, and fluctuation constraints
Extended states in a two-dimensional disordered electron gas in a strong magnetic field: energy structure, evolution with disorder, and interaction effects
Quantitative validation of the charge fractionalization fraction measured in non-chiral quantum wires
Corrections to the extrinsic spin Hall conductivity of bulk n-doped GaAs: electron-electron interactions, multiple-impurity scattering, and impurity compensation
Beyond the quadratic saddle: quantum transmission through non-quadratic saddle-point potentials in a strong magnetic field
Nonperturbative serial transport and crossover boundaries of the SU(4) Kondo state in a capacitively coupled double quantum dot
Open problems of the renormalization-group treatment of the critical dynamics of the binary-fluid and gas-liquid transitions (model H): higher-order ε expansion, controlled d = 3 amplitudes, and nonuniversal backgrounds
Microscopic determination of the vortex transport coefficients in the Ambegaokar–Halperin–Nelson–Siggia theory of dissipation in two-dimensional superfluids

Back to open problems

Boundaries of validity of dislocation-mediated melting in two dimensions: first-order versus two-stage scenarios, substrate-coupled renormalization-group flows, and quantitative control of the theory's approximations

Finite-temperature theory of spin transport through antiferromagnetic insulators: two-fluid dynamics of the magnon condensate and thermal cloud, and its experimental identification

Unresolved phase-diagram questions of the Nelson–Halperin model of a smectic layer with tilted molecules: order of symmetry-equivalent transitions, the strong-coupling fate of the unlocked tilted hexatic, and the stacking of coupled layers

Microscopic theory of the cyclotron-resonance line shape of an interacting, disordered two-dimensional electron gas beyond the leading-order, integer-filling, strong-field limit, and the origin of anomalous cyclotron-resonance splittings at intermediate magnetic fields

Quantitative theory and experimental realization of spin-diffusion-mediated nonlocal charge transport with k-linear spin-orbit coupling in the spin Hall effect regime

Realizing the parity-based diagnostics of the non-Abelian ν=5/2\nu=5/2ν=5/2 quantum Hall state in realistic devices: quasiparticle-parity control, capacitance, stability, and fluctuation constraints

Extended states in a two-dimensional disordered electron gas in a strong magnetic field: energy structure, evolution with disorder, and interaction effects

Quantitative validation of the charge fractionalization fraction measured in non-chiral quantum wires

Corrections to the extrinsic spin Hall conductivity of bulk n-doped GaAs: electron-electron interactions, multiple-impurity scattering, and impurity compensation

Beyond the quadratic saddle: quantum transmission through non-quadratic saddle-point potentials in a strong magnetic field

Nonperturbative serial transport and crossover boundaries of the SU(4) Kondo state in a capacitively coupled double quantum dot

Open problems of the renormalization-group treatment of the critical dynamics of the binary-fluid and gas-liquid transitions (model H): higher-order ε expansion, controlled d = 3 amplitudes, and nonuniversal backgrounds

Microscopic determination of the vortex transport coefficients in the Ambegaokar–Halperin–Nelson–Siggia theory of dissipation in two-dimensional superfluids

Realizing the parity-based diagnostics of the non-Abelian $\nu=5/2$ quantum Hall state in realistic devices: quasiparticle-parity control, capacitance, stability, and fluctuation constraints