Using the Lindemann criterion,we analyzed the quantum and thermal melting of electronic/excitonic crystals recently discovered in two-dimensional(2D)semiconductor moirépatterns.We show that the finite 2D screenin...Using the Lindemann criterion,we analyzed the quantum and thermal melting of electronic/excitonic crystals recently discovered in two-dimensional(2D)semiconductor moirépatterns.We show that the finite 2D screening of the atomically thin material can suppress(enhance)the inter-site Coulomb(dipolar)interaction strength,thus inhibits(facilitates)the formation of the electronic(excitonic)crystal.Meanwhile,a strong enough moiréconfinement is found to be essential for realizing the crystal phase with a wavelength near 10 nm or shorter.From the calculated Lindemann ratio which quantifies the fluctuation of the site displacement,we estimate that the crystal will melt into a liquid above a critical temperature ranging from several tens Kelvin to above 100 K(depending on the system parameters).展开更多
In this paper a stochastic series expansion quantum Monte Carlo algorithm is used to study a frustratedspin chain with diagonal next-nearest-neighbor interactions.The detailed balance conditions are carefully analyzed...In this paper a stochastic series expansion quantum Monte Carlo algorithm is used to study a frustratedspin chain with diagonal next-nearest-neighbor interactions.The detailed balance conditions are carefully analyzed toimprove the efficiency of simulation process.As an application of this algothrim,the total magnetization,the staticstructure factor and spin-stiffness are calculated for a certain set of system parameters as a function of external fieldstrength.展开更多
We analyze aspects of nuclear dark states.The formation of the dark states prevents the further establishment of nuclear polarizations,while inhomogeneous nuclear spin precessions can result in leakage from these stat...We analyze aspects of nuclear dark states.The formation of the dark states prevents the further establishment of nuclear polarizations,while inhomogeneous nuclear spin precessions can result in leakage from these states.An optimal efficiency for pumping nuclear polarization is achieved when the dynamical nuclear polarization(DNP)cycling rate is comparable to the dark-state leakage rate.When the DNP rate is much larger,the nuclear spin bath can be locked on the dark states.We propose schemes where the inhomogeneous precessions can be suppressed for the realization of large-scale dark states.As the dark states correspond to low transverse nuclear field fluctuations,they can be used to suppress the decoherence of the electron induced by the nuclear spins.展开更多
Moiré interlayer exciton in transition metal dichalcogenide heterobilayer features a permanent electric dipole that enables the electrostatic control of its flow, and optical dipole that is spatially varying in t...Moiré interlayer exciton in transition metal dichalcogenide heterobilayer features a permanent electric dipole that enables the electrostatic control of its flow, and optical dipole that is spatially varying in the moiré landscape. We show the hybridization of moiré interlayer exciton with photons in a planar 2D cavity leads to two types of moiré polaritons that exhibit distinct forms of topological transport phenomena including the spin/valley Hall and polarization Hall effects, which feature remarkable electrical tunability through the control of exciton-cavity detuning by the interlayer bias.展开更多
基金support by the National Natural Science Foundation of China(Grant No.12274477)the Department of Science and Technology of Guangdong Province of China(Grant No.2019QN01X061)。
文摘Using the Lindemann criterion,we analyzed the quantum and thermal melting of electronic/excitonic crystals recently discovered in two-dimensional(2D)semiconductor moirépatterns.We show that the finite 2D screening of the atomically thin material can suppress(enhance)the inter-site Coulomb(dipolar)interaction strength,thus inhibits(facilitates)the formation of the electronic(excitonic)crystal.Meanwhile,a strong enough moiréconfinement is found to be essential for realizing the crystal phase with a wavelength near 10 nm or shorter.From the calculated Lindemann ratio which quantifies the fluctuation of the site displacement,we estimate that the crystal will melt into a liquid above a critical temperature ranging from several tens Kelvin to above 100 K(depending on the system parameters).
基金Supported by NSFC under Grants Nos.10874235,10934010,60978019NKBRSFC under Grants Nos.2006CB921400,2009CB930704,2010CB922904
文摘In this paper a stochastic series expansion quantum Monte Carlo algorithm is used to study a frustratedspin chain with diagonal next-nearest-neighbor interactions.The detailed balance conditions are carefully analyzed toimprove the efficiency of simulation process.As an application of this algothrim,the total magnetization,the staticstructure factor and spin-stiffness are calculated for a certain set of system parameters as a function of external fieldstrength.
基金Supported by the Research Grant Council of Hong Kong under Grant No HKU 706309P.
文摘We analyze aspects of nuclear dark states.The formation of the dark states prevents the further establishment of nuclear polarizations,while inhomogeneous nuclear spin precessions can result in leakage from these states.An optimal efficiency for pumping nuclear polarization is achieved when the dynamical nuclear polarization(DNP)cycling rate is comparable to the dark-state leakage rate.When the DNP rate is much larger,the nuclear spin bath can be locked on the dark states.We propose schemes where the inhomogeneous precessions can be suppressed for the realization of large-scale dark states.As the dark states correspond to low transverse nuclear field fluctuations,they can be used to suppress the decoherence of the electron induced by the nuclear spins.
基金the Key-Area Research and Development Program of Guangdong Province(2019B030330001)Research Grants Council of Hong Kong(17312916)Seed Funding for Strategic Interdisciplinary Research Scheme of HKU。
文摘Moiré interlayer exciton in transition metal dichalcogenide heterobilayer features a permanent electric dipole that enables the electrostatic control of its flow, and optical dipole that is spatially varying in the moiré landscape. We show the hybridization of moiré interlayer exciton with photons in a planar 2D cavity leads to two types of moiré polaritons that exhibit distinct forms of topological transport phenomena including the spin/valley Hall and polarization Hall effects, which feature remarkable electrical tunability through the control of exciton-cavity detuning by the interlayer bias.
