Nuclear magnetometry studies of spin dynamics in quantum Hall systems

Fauzi, M. H.; Watanabe, Satoshi; Hirayama, Y.

doi:10.1103/physrevb.90.235308

Cited by 8 publications

(14 citation statements)

References 31 publications

(44 reference statements)

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“…One possible realization is with a nuclear spin ensemble in GaAs semiconductors coupled with the NG mode as a low-frequency electron spin fluctuation [20,21]. Here the spin dynamics in quantum dots and the quantum Hall regime has been extensively investigated [13,[25][26][27].…”

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confidence: 99%

Relaxation to Negative Temperatures in Double Domain Systems

2018

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We investigate the relaxation of two collective spins in double domain system, which are individually coupled to a single bosonic reservoir, by varying the total number of spins in each domain and their initial spin configurations. A particularly interesting situation occurs when the spin domains are set in an antiparallel configuration. Further for an unbalanced configuration where the number of spins are in the excited state initially is much greater than that in the ground state, the spin ensemble prepared in the ground state relaxes towards a negative-temperature state.PACS numbers: 42.50. Nn, Introduction.-In recent years, the hybridization of quantum systems has become a key technique to design and demonstrate novel quantum behaviors [1][2][3]. With the rapid progress in quantum coherent manipulation, hybrid quantum systems have now entered the regime where we can observe unexpected or rather counterintuitive behavior even in the presence of imperfections and noise [4][5][6][7]. Such hybrid systems have not only shown the capability to achieve superior properties each individual system alone cannot achieve [5,8], but they also shred light on the fundamental complexity of such quantum systems including coupling structures and decoherence mechanisms [9]. Currently a number of such hybrid systems have been proposed (and realized in some cases) with various elements coming from atomic molecular & optical systems to solid-state systems. Example include for instance, trapped ions [10], optical cavities & resonators [11,12], electron and nuclear spin ensembles in quantum dots (QD) or nitrogen-vacancy centers in diamond [13][14][15], superconducting circuits in quantum electrodynamic systems [2] and mechanical resonators [15,16]. This large diversity of component systems really allows one to explore the unique space hybridization potentially allows.

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confidence: 99%

Relaxation to Negative Temperatures in Double Domain Systems

2018

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“…The candidate hybrid quantum systems to observe these phenomena are, one is the GaAs semiconductor where nuclear spins are coupling to the electron spins in the QH state through the hyperfine interaction. When we initially prepared the nuclear double spin domain having antiparallel configuration induced by the DNP [22,23], by tuning the QH state so that the linear dispersing NG mode as the bosonic reservoir emerge [24][25][26], we observe our collective phenomena. The second candidate is the electron spin ensemble in the NV center in diamonds coupling to the superconducting resonator [27].…”

Section: Discussionmentioning

confidence: 99%

Negative-temperature-state relaxation and reservoir-assisted quantum entanglement in double-spin-domain systems

Hama¹,

Yukawa²,

Munro³

et al. 2018

Phys. Rev. A

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Spin collective phenomena including superradiance are even today being intensively investigated with experimental tests performed based on state-of-the-art quantum technologies. Such attempts are not only for the simple experimental verification of predictions from the last century but also as a motivation to explore new applications of spin collective phenomena and the coherent control of the coupling between spin ensembles and reservoirs. In this paper, we investigate the open quantum dynamics of two spin ensembles (double spin domains) coupled to a common bosonic reservoir. We analyze in detail the dynamics of our collective state and its structure by focusing on both the symmetry and asymmetry of this coupled spin system. We find that when the spin size of one of the double domains is larger than that of the other domain, at the steady state this system exhibits two novel collective behaviors: the negative-temperature state relaxation in the smaller spin domain and the reservoir-assisted quantum entanglement between the two domains. These results are the consequence of the asymmetry of this system and the decoherence driven by the common reservoir.

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“…It has been shown that the nuclear-spin relaxation time in the CAF phase is the shortest compared with those in the other two phases (the ferromagnetic phase and the spin-singlet phase). More recent experiment [12], where the spatial nuclear-spin polarization distribution was recorded after the exposure to the CAF phase, showed a sudden change in the nuclear-spin polarization distribution from the initial one. These experimental results suggest a unique many-body interaction between electron and nuclear spin systems.…”

Section: Introductionmentioning

confidence: 94%

“…The above situation may change when the nuclear spins interact coherently with low-energy excitation modes of electron spins such as Nambu-Goldstone (NG) modes. For instance, the NG modes appear in the canted antiferromagnetic (CAF) phase [4][5][6][7][8][9][10][11][12] due to the spontaneous breaking of the rotational U(1) symmetry. This phase is the most interesting one among the three phases of the total filling factor 2 n = bilayer QH systems: the ferromagnetic phase, the spin-singlet phase and the CAF phase.…”

Section: Introductionmentioning

confidence: 99%

“…In this paper, motivated by the experiments [10,12], as the first step of studying the electron-nuclear spin dynamics in the QH system as a hybrid quantum system, we theoretically study the interaction between the nuclear spins and the linear dispersing NG mode associated with the U(1) spin rotational symmetry breaking, a schematic illustration of this model is shown in figure 1. To make a detailed analysis and to clearly understand its physics behind, we focus on the CAF phase in the 2 n = bilayer QH system.…”

Section: Introductionmentioning

confidence: 99%

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Dicke model for quantum Hall systems

et al. 2016

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In GaAs quantum Hall (QH) systems, electrons are coupled with nuclear spins through the hyperfine interaction, which is normally not strong enough to change the dynamics of electrons and nuclear spins. The dynamics of the QH systems, however, may drastically change when the nuclear spins interact with low-energy collective excitation modes of the electron spins. We theoretically investigate the nuclear-electron spin interaction in the QH systems as hybrid quantum systems driven by the hyperfine interaction. In particular, we study the interaction between the nuclear spins and the Nambu-Goldstone (NG) mode with the linear dispersion relation associated with the U(1) spin rotational symmetry breaking. We show that such an interaction is described as nuclear spins collectively coupled to the NG mode, and can be effectively described by the Dicke model. Based on the model we suggest that various collective spin phenomena realized in quantum optical systems can also emerge in the QH systems.

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Nuclear magnetometry studies of spin dynamics in quantum Hall systems

Cited by 8 publications

References 31 publications

Relaxation to Negative Temperatures in Double Domain Systems

Relaxation to Negative Temperatures in Double Domain Systems

Negative-temperature-state relaxation and reservoir-assisted quantum entanglement in double-spin-domain systems

Dicke model for quantum Hall systems

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