Tunable phonon-induced steady-state coherence in a double-quantum-dot charge qubit

Purkayastha, Archak; Guarnieri, Giacomo; Mitchison, Mark T.; Filip, Radim; Goold, John

doi:10.1038/s41534-020-0256-6

Cited by 59 publications

(92 citation statements)

References 61 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…of the global system-plus-reservoir Gibbs state τ SR ðβÞ at inverse temperature β ¼ 1=k B T. The predictions of strong coupling thermodynamics differ from standard thermodynamics because the MFG state can deviate significantly from the standard Gibbs state τ S ðβÞ ∝ e −βH S widely used across all of the natural sciences. Apart from leading to corrections to the state's probabilities, the systemreservoir coupling can lead to ρ S maintaining coherences with respect to the basis of H S at low and intermediate temperatures [26]. This is significant because coherences are often viewed as an indication of the quantumness of a system and considered a quantum "resource" [27].…”

mentioning

confidence: 99%

“…This is significant because coherences are often viewed as an indication of the quantumness of a system and considered a quantum "resource" [27]. Beyond quantum thermodynamics [26,[28][29][30][31][32], coherences play an important role in some biological processes [33][34][35][36][37], and may also affect a material's magnetization behavior [38]. But beyond a few limited examples, the explicit evaluation of the reduced state ρ S has generally proven intractable.…”

mentioning

confidence: 99%

See 1 more Smart Citation

Weak and Ultrastrong Coupling Limits of the Quantum Mean Force Gibbs State

Cresser

Anders

2021

Phys. Rev. Lett.

View full text Add to dashboard Cite

The Gibbs state is widely taken to be the equilibrium state of a system in contact with an environment at temperature T. However, non-negligible interactions between system and environment can give rise to an altered state. Here, we derive general expressions for this mean force Gibbs state, valid for any system that interacts with a bosonic reservoir. First, we derive the state in the weak coupling limit and find that, in general, it maintains coherences with respect to the bare system Hamiltonian. Second, we develop a new expansion method suited to investigate the ultrastrong coupling regime. This allows us to derive the explicit form for the mean force Gibbs state, and we find that it becomes diagonal in the basis set by the systemreservoir interaction instead of the system Hamiltonian. Several examples are discussed including a single qubit, a three-level V-system, and two coupled qubits all interacting with bosonic reservoirs. The results shed light on the presence of coherences in the strong coupling regime, and provide key tools for nanoscale thermodynamics investigations.

show abstract

mentioning

confidence: 99%

mentioning

confidence: 99%

Weak and Ultrastrong Coupling Limits of the Quantum Mean Force Gibbs State

Cresser

Anders

2021

Phys. Rev. Lett.

View full text Add to dashboard Cite

show abstract

“…The effect of the substrate phonons on the DQD, as well as the spectral function for the phonons, can vary depending on the platform. They have been well characterized in literature both theoretically [102,106,107] and experimentally [103,108]. The spectral function J ph (ω) in Eq.…”

Section: Microscopic Hamiltonian For the Dqd Coupled To Circuit-qmentioning

confidence: 99%

Emergent PT symmetry in a double-quantum-dot circuit QED setup

Purkayastha

Kulkarni

Joglekar

2020

Phys. Rev. Research

Self Cite

View full text Add to dashboard Cite

Open classical and quantum systems with effective parity-time (PT) symmetry, over the past five years, have shown tremendous promise for advances in lasers, sensing, and nonreciprocal devices. And yet, how such effective PT-symmetric non-Hermitian models emerge out of Hermitian quantum mechanics is not well understood. Here, starting from a fully Hermitian microscopic Hamiltonian description, we show that a non-Hermitian Hamiltonian emerges naturally in a double-quantum-dot (DQD) circuit-QED setup, which can be controllably tuned to the PT-symmetric point. This effective Hamiltonian governs the dynamics of two coupled circuit-QED cavities with a voltage-biased DQD in one of them. Our analysis also reveals the effect of quantum fluctuations on the PT-symmetric system. The PT transition is, then, observed both in the dynamics of cavity observables as well as via an input-output experiment. As a simple application of the PT transition in this setup, we show that loss-induced enhancement of amplification and lasing can be observed in the coupled cavities. By comparing our results with two conventional local Lindblad equations, we demonstrate the utility and limitations of the latter. Our results pave the way for an on-chip realization of a potentially scalable non-Hermitian system with a gain medium in the quantum regime, as well as its potential applications for quantum technology.

show abstract

“…Even though phonons can be responsible for the decoherence of qubits (Kornich et al, 2018), there is some indication that they may also play a positive role in the quantum information industry. Research has shown that robust coherence can be maintained in a double quantum dot system due to the presence of phonons (Purkayastha et al, 2020). Recently, phonons have been used to couple distant quantum systems, facilitating quantum entanglement of two qubits (Bienfait et al, 2019).…”

Section: Introductionmentioning

confidence: 99%

Electron-LO-phonon Intrasubband Scattering Rates in a Hollow Cylinder Under the Influence of a Uniform Axial Applied Magnetic Field

Masale

Tshipa

2021

Preprint

View full text Add to dashboard Cite

Scattering rates arising from the interactions of electrons with bulk longitudinal optical (LO) phonon modes in a hollow cylinder are calculated as functions of the inner radius and the uniform axial applied magnetic field. Now, the specific nature of electron-phonon interactions mainly depends on the character of the energy spectrum of electrons. As is well known, in cylindrical quantum wires, the application of a parallel magnetic field lifts the double degeneracy of the non-zero azimuthal quantum number states; m≠0; irrespective of all electron's radial quantum number l states. In fact, this Zeeman splitting is such that the m < 0 electron's energy subbands initially decrease with the increase of the parallel applied magnetic field. In a solid cylinder, the lowest-order; {l = 1; m = 0} subband is always the ground state. In a hollow cylinder, however, as the axial applied magnetic field is increased, the electron's energy subbands take turns at becoming the ground state; following the sequence {m=0,-1,-2...-N} of azimuthal quantum numbers. Furthermore, in a hollow cylinder, in general, the electron's energy separations between any two subbands are less than the LO phonon energy except for exceptionally high magnetic fields, and some highest-order quantum number states. In view of this, the discussion of the energy relaxation here is focused mainly on intrasubband scattering of electrons and only within the lowest-order {l = 1; m = 0} electron's energy subband. The intrasubband scattering rates are found to be characterized by shallow minima in their variations with the inner radius, again, for a fixed outer radius. This feature is a consequence of a balance between two seemingly conflicting effects of the electron's confinement by the inner and outer walls of the hollow cylinder. First; increased confinement of the charge carriers generally leads to the enhancement of the rates. Second; the presence of a hole in a hollow cylinder leads to a significant suppression of the scattering rates. The intrasubband scattering rates also show a somewhat parabolic increase in their variations with the applied magnetic field; an increase which is more pronounced in a relatively thick hollow cylinder.

show abstract

Tunable phonon-induced steady-state coherence in a double-quantum-dot charge qubit

Cited by 59 publications

References 61 publications

Weak and Ultrastrong Coupling Limits of the Quantum Mean Force Gibbs State

Weak and Ultrastrong Coupling Limits of the Quantum Mean Force Gibbs State

Emergent PT symmetry in a double-quantum-dot circuit QED setup

Electron-LO-phonon Intrasubband Scattering Rates in a Hollow Cylinder Under the Influence of a Uniform Axial Applied Magnetic Field

Contact Info

Product

Resources

About