Tunable quantum phase transitions in a resonant level coupled to two dissipative baths

Liu, Dong E.; Zheng, Haizhong; Finkelstein, Gleb; Baranger, Harold U.

doi:10.1103/physrevb.89.085116

Cited by 28 publications

(44 citation statements)

References 81 publications

(237 reference statements)

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“…This "freezing" of Φ s indicates that the dot spin at low temperatures becomes fully screened. Similar freezing mechanisms have been reported before in, e.g, Luttinger liquid quantum wires [91,105,108], dissipative resonant level models [112,113], as well as topological Kondo systems [114,115]. The z-component of the interedge Kondo exchange Jz 2 always has scaling dimension (K+1/K)/2, regardless of the value of Jz 1 .…”

Section: B Kondo Tunnelingsupporting

confidence: 82%

Does delta-$T$ noise probe quantum statistics?

Z¹,

Gornyi²,

Spånslätt³

2022

Preprint

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We study delta-T noise-excess charge noise at zero voltage but finite temperature bias-for weak tunneling in one-dimensional interacting systems. We show that the sign of the delta-T noise is generically determined by the nature of the dominating tunneling process. More specifically, the sign is governed by the leading charge-tunneling operator's scaling dimension. We clarify the relation between the sign of delta-T noise and the quantum exchange statistics of tunneling quasiparticles. We find that, for infinite systems hosting chiral channels with local interactions (e.g., quantum Hall or quantum spin Hall edges), when the delta-T noise is negative, the tunneling particles are boson-like, revealing their tendency towards bunching. However, the opposite is not true: Bosonlike particles do not necessarily produce negative delta-T noise. Importantly, the bosonic nature of particles generating the negative delta-T is not necessarily intrinsic, but can be induced by the interactions. This, in particular, implies that negative delta-T noise for tunneling between the edge states cannot serve as a smoking gun for detecting "intrinsic anyons". We also establish a connection between the delta-T noise and the temperature derivative of the Nyquist-Johnson (thermal) noise in interacting systems, both governed by the same scaling dimensions. As a demonstration of the above statements, we study tunneling between two interacting quantum spin Hall edges. With bosonization and renormalization-group techniques, we find that many-body interactions can generate negative delta-T noise for both direct tunneling through a point contact and in Kondo exchange tunneling via a localized spin. In both these setups, we show that the noise can become negative at sufficiently low temperatures, when interactions renormalize the tunneling to favor boson-like pair-tunneling of electrons rather than single-electron tunneling. Our findings show that delta-T noise can be used to probe the nature of collective excitations in interacting one-dimensional systems.

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Section: B Kondo Tunnelingsupporting

confidence: 82%

Does delta-$T$ noise probe quantum statistics?

Z¹,

Gornyi²,

Spånslätt³

2022

Preprint

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“…(6) and (9) and noting that the unitary operator applied in Sec. II C does not affect the current operator [28], we find…”

Section: A Current Operator In Majorana Termsmentioning

confidence: 56%

Transport signatures of Majorana quantum criticality realized by dissipative resonant tunneling

Zheng

Florens²,

Baranger³

2014

Phys. Rev. B

Self Cite

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We consider theoretically the transport properties of a spinless resonant electronic level coupled to strongly dissipative leads, in the regime of circuit impedance near the resistance quantum. Using the Luttinger liquid analogy, one obtains an effective Hamiltonian expressed in terms of interacting Majorana fermions, in which all environmental degrees of freedom (leads and electromagnetic modes) are encapsulated in a single fermionic bath. General transport equations for this system are then derived in terms of the Majorana T-matrix. Perturbative treatment of the Majorana interaction term yields the appearance of a marginal, linear dependence of the conductance on temperature when the system is tuned to its quantum critical point, in agreement with recent experimental observations. We investigate in detail the different crossovers involved in the problem, and analyze the role of the interaction terms in the transport scaling functions. In particular, we show that single barrier scaling applies when the system is slightly tuned away from its Majorana critical point, strengthening the general picture of dynamical Coulomb blockade.

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“…An Ohmic bosonic bath can be engineered through a long transmission line [15,16]. Another setup of interest is a one-dimensional Luttinger liquid [18,19], where a dissipative quantum phase transition were recently observed [62,63]. Cold atom setups [17,64,65] are also viable candidates to simulate an Ohmic bath coupled to a two-level system.…”

Section: Conclusion and Experimental Perspectivesmentioning

confidence: 99%

Topology of a dissipative spin: Dynamical Chern number, bath-induced nonadiabaticity, and a quantum dynamo effect

et al. 2017

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We analyze the topological deformations of the ground state manifold of a quantum spin-1/2 in a magnetic field H = H(sin theta cos phi, sin theta sin phi cos theta) induced by a coupling to an ohmic quantum dissipative environment at zero temperature. From Bethe ansatz results and a variational approach, we confirm that the Chern number associated with the geometry of the reduced spin ground state manifold is preserved in the delocalized phase for alpha < 1. We report a divergence of the Berry curvature at alpha(c) = 1 for magnetic fields aligned along the equator theta = pi/2. This divergence is caused by the complete quenching of the transverse magnetic field by the bath associated with a gap closing that occurs at the localization Kosterlitz-Thouless quantum phase transition in this model. Recent experiments in quantum circuits have engineered nonequilibrium protocols to access topological properties from a measurement of a dynamical Chern number defined via the out-of-equilibrium spin expectation values. Applying a numerically exact stochastic Schrodinger approach we find that, for a fixed field sweep velocity theta(t) = vt, the bath induces a crossover from ( quasi) adiabatic to nonadiabatic dynamical behavior when the spin bath coupling a increases. We also investigate the particular regime H/omega(c) << v/H << 1 with large bath cutoff frequency.c, where the dynamical Chern number vanishes already at alpha = 1/2. In this regime, the mapping to an interacting resonance level model enables us to analytically describe the behavior of the dynamical Chern number in the vicinity of alpha = 1/2. We further provide an intuitive physical explanation of the bath-induced breakdown of adiabaticity in analogy to the Faraday effect in electromagnetism. We demonstrate that the driving of the spin leads to the production of a large number of bosonic excitations in the bath, which strongly affect the spin dynamics. Finally, we quantify the spin-bath entanglement and formulate an analogy with an effective model at thermal equilibrium. Disciplines Condensed Matter Physics | Physics CommentsThis article is published as Henriet, Loïc, Antonio Sclocchi, Peter P. Orth, and Karyn Le Hur. "Topology of a dissipative spin: Dynamical Chern number, bath-induced nonadiabaticity, and a quantum dynamo effect." Physical Review B 95, no. 5 (2017) We analyze the topological deformations of the ground state manifold of a quantum spin-1/2 in a magnetic field H = H (sin θ cos φ, sin θ sin φ, cos θ ) induced by a coupling to an ohmic quantum dissipative environment at zero temperature. From Bethe ansatz results and a variational approach, we confirm that the Chern number associated with the geometry of the reduced spin ground state manifold is preserved in the delocalized phase for α < 1. We report a divergence of the Berry curvature at α c = 1 for magnetic fields aligned along the equator θ = π/2. This divergence is caused by the complete quenching of the transverse magnetic field by the bath associated with a gap closing that occurs a...

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Tunable quantum phase transitions in a resonant level coupled to two dissipative baths

Cited by 28 publications

References 81 publications

Does delta-$T$ noise probe quantum statistics?

Does delta-$T$ noise probe quantum statistics?

Transport signatures of Majorana quantum criticality realized by dissipative resonant tunneling

Topology of a dissipative spin: Dynamical Chern number, bath-induced nonadiabaticity, and a quantum dynamo effect

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