Chinese Physics B

Decoherence in the Pure Dephasing Spin-Boson Model with Hermitian or Non-Hermitian Bath

Ying Wu, Ning-Hua Tong

Published Mar 12, 2026• 0 citations

Abstract

Abstract In this paper, we investigate the decoherence of qubit due to its coupling to a Hermitian or a non-Hermitian environment within the pure dephasing spin-boson model. Using this model, we analytically establish the previously anticipated similarity between the non-equilibrium and the equilibrium correlation functions $P_x(t)$ and $C_x(t)$. We find that integer values of $A$ (coupling strength) or $s$ (bath exponent) has distinctive long time asymptotic behaviors of $P_x(t)$ and $C_x(t)$ from those of the non-integer values, accompanied with a diverging crossover time scale. We also find that the non-Hermitian environment tends to suppress the decoherence of qubit for all values of $A$ and $s$, in contrast to the conclusion of Dey et al . [Phys. Lett. A 383, 125931 (2019)]. Our results show the potential of the non-Hermitian environmental engineering for suppressing the decoherence of qubit.

DOI: 10.1088/1674-1056/ae50df

Related papers

Decoherence in the Pure Dephasing Spin-Boson Model with Hermitian or Non-Hermitian Bath

Yue-Hong Wu, Ning-Hua Tong

quant-pharXiv:2512.15297Dec 18, 20250 citations

Decoherence in a $\mathcal{PT}$-symmetric qubit

Junaid Majeed Bhat, Muzaffar Qadir Lone, Sanjoy Datta +1 more

arXiv:1712.02554Dec 7, 20170 citations

Suppression of Decoherence at Exceptional Transitions

Mei-Lin Li, Zuo Wang, Liang He

quant-pharXiv:2602.01123Feb 3, 20260 citations

Decoherence in a PT -Symmetric Qubit

Junaid Majeed Bhat, Muzaffar Qadir Lone, Sanjoy Datta +2 more

Ukrainian Journal of PhysicsApr 20, 20232 citations

Bath dynamics in an exactly solvable qubit model with initial qubit-environment correlations

V. V. Ignatyuk, Morozov

arXiv:1310.1236Condensed Matter PhysicsJan 1, 201310 citations

Interference of qubits in pure dephasing and almost pure dephasing environments

Marcin Łobejko, Marcin Mierzejewski, Jerzy Dajka

Journal of Physics A Mathematical and TheoreticalJun 16, 20154 citations

Chinese Physics B

Decoherence in the Pure Dephasing Spin-Boson Model with Hermitian or Non-Hermitian Bath

Ying Wu, Ning-Hua Tong

Published Mar 12, 2026• 0 citations

Publisher

Abstract

P_x(t)

and

C_x(t)

. We find that integer values of

A

(coupling strength) or

s

(bath exponent) has distinctive long time asymptotic behaviors of

P_x(t)

and

C_x(t)

from those of the non-integer values, accompanied with a diverging crossover time scale. We also find that the non-Hermitian environment tends to suppress the decoherence of qubit for all values of

A

and

s

, in contrast to the conclusion of Dey et al . [Phys. Lett. A 383, 125931 (2019)]. Our results show the potential of the non-Hermitian environmental engineering for suppressing the decoherence of qubit.

DOI: 10.1088/1674-1056/ae50df

Related papers

Decoherence in the Pure Dephasing Spin-Boson Model with Hermitian or Non-Hermitian Bath

Yue-Hong Wu, Ning-Hua Tong

In this paper, we investigate the decoherence of qubit due to its coupling to a Hermitian or a non-Hermitian bath within the pure dephasing spin-boson model. First, using this model, we analytically establish the previously anticipated similarity between the non-equilibrium and the equilibrium correlation functions $P_x(t)$ and $C_x(t)$ . Then, in the short/long time asymptotic behaviors of $P_x(t)$ , we find singular dependence on $A$ (coupling strength) and $s$ (bath exponent) at their integer values. Finally, we find that the non-Hermitian bath tends to suppress the decoherence of qubit for all values of $A$ and $s$ , in contrast to the conclusion of Dey et al. . Our results show the potential of non-Hermitian environment engineering in suppressing the decoherence of qubit.In this paper, we investigate the decoherence of qubit due to its coupling to a Hermitian or a non-Hermitian bath within the pure dephasing spin-boson model. First, using this model, we analytically establish the previously anticipated similarity between the non-equilibrium and the equilibrium correlation functions $P_x(t)$ and $C_x(t)$. Then, in the short/long time asymptotic behaviors of $P_x(t)$, we find singular dependence on $A$ (coupling strength) and $s$ (bath exponent) at their integer values. Finally, we find that the non-Hermitian bath tends to suppress the decoherence of qubit for all values of $A$ and $s$, in contrast to the conclusion of Dey et al. . Our results show the potential of non-Hermitian environment engineering in suppressing the decoherence of qubit.

quant-pharXiv:2512.15297Dec 18, 20250 citations

Decoherence in a $\mathcal{PT}$ -symmetric qubitDecoherence in a $\mathcal{PT}$-symmetric qubit

Junaid Majeed Bhat, Muzaffar Qadir Lone, Sanjoy Datta +1 more

We investigate the decoherence in a $\mathcal{PT}$ -symmetric qubit coupled with a bosonic bath. Using cannonical transformations, we map the non-Hermitian Hamiltonian representing the $\mathcal{PT}$ -symmetric qubit to a spin boson model. Identifying the parameter α that demarcates the hermiticity and non-hermiticity in the model, we show that the qubit does not decohere at the transition from real eigen spectrum to complex eigen spectrum. Using a general class of spectral densities, the strong suppression of decoherence is observed due to both vaccum and thermal fluctuations of the bath, and initial correlations as we approach the transition point.We investigate the decoherence in a $\mathcal{PT}$-symmetric qubit coupled with a bosonic bath. Using cannonical transformations, we map the non-Hermitian Hamiltonian representing the$\mathcal{PT}$-symmetric qubit to a spin boson model. Identifying the parameter α that demarcates the hermiticity and non-hermiticity in the model, we show that the qubit does not decohere at the transition from real eigen spectrum to complex eigen spectrum. Using a general class of spectral densities, the strong suppression of decoherence is observed due to both vaccum and thermal fluctuations of the bath, and initial correlations as we approach the transition point.

arXiv:1712.02554Dec 7, 20170 citations

Suppression of Decoherence at Exceptional Transitions

Mei-Lin Li, Zuo Wang, Liang He

Decoherence is strongly influenced by environmental criticality, with conventional Hermitian critical points typically enhancing the loss of quantum coherence. Here, we show that this paradigm is fundamentally altered in non-Hermitian environments. Focusing on qubits coupled to non-Hermitian spin chains and interacting ultracold Fermi gases, we find that approaching exceptional points can either enhance or strongly suppress decoherence, depending on the balance between Hermitian and non-Hermitian system-environment couplings. In particular, when these couplings are comparable, decoherence is dramatically suppressed at exceptional transitions. We trace this behavior to the distinct response of the environmental ground state near non-Hermitian degeneracies and demonstrate the robustness of this effect across multiple models. Finally, we show that the predicted suppression of decoherence is directly observable on current digital quantum simulation platforms. Our results establish exceptional points as a concrete mechanism for suppressing decoherence and identify non-Hermitian criticality as a new avenue for coherence control in open quantum systems and quantum technologies.Decoherence is strongly influenced by environmental criticality, with conventional Hermitian critical points typically enhancing the loss of quantum coherence. Here, we show that this paradigm is fundamentally altered in non-Hermitian environments. Focusing on qubits coupled to non-Hermitian spin chains and interacting ultracold Fermi gases, we find that approaching exceptional points can either enhance or strongly suppress decoherence, depending on the balance between Hermitian and non-Hermitian system-environment couplings. In particular, when these couplings are comparable, decoherence is dramatically suppressed at exceptional transitions. We trace this behavior to the distinct response of the environmental ground state near non-Hermitian degeneracies and demonstrate the robustness of this effect across multiple models. Finally, we show that the predicted suppression of decoherence is directly observable on current digital quantum simulation platforms. Our results establish exceptional points as a concrete mechanism for suppressing decoherence and identify non-Hermitian criticality as a new avenue for coherence control in open quantum systems and quantum technologies.

quant-pharXiv:2602.01123Feb 3, 20260 citations

Decoherence in a PT -Symmetric Qubit

Junaid Majeed Bhat, Muzaffar Qadir Lone, Sanjoy Datta +2 more

We investigate the decoherence in a PT -symmetric qubit coupled with a bosonic bath. Using canonical transformations, we map the non-Hermitian Hamiltonian representing the PT-symmetric qubit to a spin boson model. Identifying the parameter α that demarcates the hermiticity and non-hermiticity in the model, we show that the qubit does not decohere at the transition from the real eigen spectrum to a complex eigen spectrum. Using a general class of spectral densities, the strong suppression of the decoherence is observed due to both vacuum and thermal fluctuations of the bath, and the initial correlations hold, as we approach the transition point.We investigate the decoherence in a PT -symmetric qubit coupled with a bosonic bath. Using canonical transformations, we map the non-Hermitian Hamiltonian representing the PT-symmetric qubit to a spin boson model. Identifying the parameter α that demarcates the hermiticity and non-hermiticity in the model, we show that the qubit does not decohere at the transition from the real eigen spectrum to a complex eigen spectrum. Using a general class of spectral densities, the strong suppression of the decoherence is observed due to both vacuum and thermal fluctuations of the bath, and the initial correlations hold, as we approach the transition point.

Ukrainian Journal of PhysicsApr 20, 20232 citations

Bath dynamics in an exactly solvable qubit model with initial qubit-environment correlations

V. V. Ignatyuk, Morozov

We study the bath dynamics in the dephasing model of a two-state quantum system (qubit) coupled to an environment of harmonic oscillators.This model was shown [Morozov et al., Phys.Rev. A, 2012 85, 022101] to admit the analytic solution for the qubit and environment dynamics.Using this solution, we derive the exact expression for the bath reduced density matrix in the presence of initial qubit-environment correlations.We obtain the non-equilibrium phonon distribution function and discuss in detail the time behavior of the bath energy.It is shown that only the inclusion of dynamic correlations between the qubit and the bath ensures the proper time behavior of the quantity which may be interpreted as the "environment energy".We study the bath dynamics in the dephasing model of a two-state quantum system (qubit) coupled to an environment of harmonic oscillators.This model was shown [Morozov et al., Phys.Rev. A, 2012 85, 022101] to admit the analytic solution for the qubit and environment dynamics.Using this solution, we derive the exact expression for the bath reduced density matrix in the presence of initial qubit-environment correlations.We obtain the non-equilibrium phonon distribution function and discuss in detail the time behavior of the bath energy.It is shown that only the inclusion of dynamic correlations between the qubit and the bath ensures the proper time behavior of the quantity which may be interpreted as the "environment energy".

arXiv:1310.1236Condensed Matter PhysicsJan 1, 201310 citations

Interference of qubits in pure dephasing and almost pure dephasing environments

Marcin Łobejko, Marcin Mierzejewski, Jerzy Dajka

Two-path interference of quantum particles with internal spin (qubits) interacting on one arm of the interferometer with bosonic environment is studied. It is assumed that the energy exchange between the qubit and its environment is either absent, which is a pure dephasing (decoherence) model, or very weak. Both the amplitude and the position of maximum of an output intensity discussed as a function of a phase shift can serve as a quantifier of parameters describing coupling between qubit and its environment. The time evolution of the qubit–environment system is analyzed in the Schrödinger picture and the output intensity for qubit–environment interaction close to pure decoherence is analyzed by means of perturbation theory. Quality of the applied approximation is verified by comparison with numerical results.Two-path interference of quantum particles with internal spin (qubits) interacting on one arm of the interferometer with bosonic environment is studied. It is assumed that the energy exchange between the qubit and its environment is either absent, which is a pure dephasing (decoherence) model, or very weak. Both the amplitude and the position of maximum of an output intensity discussed as a function of a phase shift can serve as a quantifier of parameters describing coupling between qubit and its environment. The time evolution of the qubit–environment system is analyzed in the Schrödinger picture and the output intensity for qubit–environment interaction close to pure decoherence is analyzed by means of perturbation theory. Quality of the applied approximation is verified by comparison with numerical results.

Journal of Physics A Mathematical and TheoreticalJun 16, 20154 citations

P_x(t)

and

C_x(t)

. We find that integer values of

A

(coupling strength) or

s

(bath exponent) has distinctive long time asymptotic behaviors of

P_x(t)

and

C_x(t)

from those of the non-integer values, accompanied with a diverging crossover time scale. We also find that the non-Hermitian environment tends to suppress the decoherence of qubit for all values of

A

and

s

P_x(t)

and

C_x(t)

. Then, in the short/long time asymptotic behaviors of

P_x(t)

, we find singular dependence on

A

(coupling strength) and

s

(bath exponent) at their integer values. Finally, we find that the non-Hermitian bath tends to suppress the decoherence of qubit for all values of

A

and

s

, in contrast to the conclusion of Dey et al. . Our results show the potential of non-Hermitian environment engineering in suppressing the decoherence of qubit.

Decoherence in a

\mathcal{PT}

-symmetric qubit

We investigate the decoherence in a

\mathcal{PT}

-symmetric qubit coupled with a bosonic bath. Using cannonical transformations, we map the non-Hermitian Hamiltonian representing the

\mathcal{PT}

-symmetric qubit to a spin boson model. Identifying the parameter α that demarcates the hermiticity and non-hermiticity in the model, we show that the qubit does not decohere at the transition from real eigen spectrum to complex eigen spectrum. Using a general class of spectral densities, the strong suppression of decoherence is observed due to both vaccum and thermal fluctuations of the bath, and initial correlations as we approach the transition point.