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arXiv:2510.17048 · Advanced Quantum Technologies

Preserving Quantum Coherence in Thermal Noisy Systems Via Qubit Frequency Modulation

Mahshid Khazaei Shadfar, Farzam Nosrati, Ali Mortezapour, Vincenzo Macrí, Roberto Morandotti, Rosario Lo Franco

Published Jun 1, 2026• 0 citations
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Abstract

ABSTRACT Quantum coherence is a key resource underpinning quantum technologies, yet it is highly susceptible to environmental decoherence, especially in thermal settings. While frequency modulation (FM) has shown promise in preserving coherence at zero temperature, its effectiveness in realistic, noisy thermal environments remains unclear. In this work, we investigate a single frequency‐modulated qubit interacting with a thermal phase‐covariant reservoir composed of dissipative and dephasing channels. We demonstrate that FM significantly preserves coherence in the presence of thermal dissipation while being ineffective under thermal pure‐dephasing noise due to commutation between system and interaction Hamiltonians. When both noise channels are present, FM offers protection only for weak dephasing coupling. Our findings clarify the limitations and potential of FM‐based coherence protection under thermal noise, supplying practical insights into designing robust quantum systems for quantum applications.

DOI
10.1002/qute.70349

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ABSTRACT Quantum coherence is a key resource underpinning quantum technologies, yet it is highly susceptible to environmental decoherence, especially in thermal settings. While frequency modulation (FM) has shown promise in preserving coherence at zero temperature, its effectiveness in realistic, noisy thermal environments remains unclear. In this work, we investigate a single frequency‐modulated qubit interacting with a thermal phase‐covariant reservoir composed of dissipative and dephasing channels. We demonstrate that FM significantly preserves coherence in the presence of thermal dissipation while being ineffective under thermal pure‐dephasing noise due to commutation between system and interaction Hamiltonians. When both noise channels are present, FM offers protection only for weak dephasing coupling. Our findings clarify the limitations and potential of FM‐based coherence protection under thermal noise, supplying practical insights into designing robust quantum systems for quantum applications.
Quantum coherence is a key resource underpinning quantum technologies, yet it is highly susceptible to environmental decoherence, especially in thermal settings. While frequency modulation (FM) has shown promise in preserving coherence at zero temperature, its effectiveness in realistic, noisy thermal environments remains unclear. In this work, we investigate a single frequency-modulated qubit interacting with a thermal phase-covariant reservoir composed of dissipative and dephasing channels. We demonstrate that FM significantly preserves coherence in the presence of thermal dissipation while being ineffective under thermal pure-dephasing noise due to commutation between system and interaction Hamiltonians. When both noise channels are present, FM offers protection only for weak dephasing coupling. Our findings clarify the limitations and potential of FM-based coherence protection under thermal noise, supplying practical insights into designing robust quantum systems for quantum applications.
Abstract We present a comprehensive study of quantum coherence dynamics in a qubit–qutrit system coupled to a resonator and exposed to an external noisy environment. Unlike prior works, we focus on the comparative analysis of three distinct coherence measures–l 1-norm of coherence, relative entropy of coherence, and Jensen–Shannon coherence–under dynamic modulation of the resonator frequency. Our key innovation lies in introducing time-dependent sinusoidal and standing wave modulations to the oscillator frequency, revealing nontrivial effects on coherence preservation that are highly sensitive to the modulation parameters. Remarkably, we uncover parameter regimes where coherence revivals are enhanced, even under strong decoherence, a phenomenon not observed in static systems. Additionally, our results demonstrate distinct sensitivity patterns among the coherence measures, highlighting their complementary roles in capturing system-environment interactions. This reanalysis is crucial as it reveals previously unexplored mechanisms for coherence control in hybrid quantum systems, offering novel strategies for improving the robustness of quantum technologies against environmental disturbances.
Finding strategies to preserve quantum resources in open systems is nowadays a main requirement for reliable quantum-enhanced technologies. We address this issue by considering structured cavities embedding qubits whose transition frequency is modulated by a driving field. We first focus on a single-qubit system to determine the optimal modulation parameters and the qubit-cavity coupling regime allowing a long-time preservation of both coherence and quantum Fisher information. We relate this behavior to the inhibition of the qubit effective decay rate rather than to stronger memory effects (non-Markovianity) of the system. We then use these findings to efficiently control resources like entanglement, discord and coherence in a system of two separated qubits. We discuss the feasibility of the system and show that individual qubit frequency modulation can produce quantum resource lifetimes orders of magnitude longer than their natural (uncontrolled) decay times. These results provide new useful insights towards efficient experimental strategies against decoherence.
ABSTRACT This research examines the dynamics of quantum correlations in a hybrid qubit–qutrit system subjected to an Ohmic noisy environment. While entanglement degradation in homogeneous systems is well‐documented, the behavior of disparate‐dimensional interfaces remains a critical challenge for the interoperability of future quantum networks. Using the negativity as a measure of entanglement, we analytically and numerically investigate how the spectral properties of the reservoir influence the system´s coherence. Our results reveal that the cut‐off frequency ω c acts as a fundamental control parameter: at low frequencies, it triggers non‐Markovian effects that effectively shield the system from entanglement sudden death, whereas high frequencies accelerate the transition to a purely dissipative regime. Furthermore, we demonstrate that strategic optimization of the coupling strength J and the entanglement parameter r can significantly enhance the robustness of hybrid correlations. The findings provide new methodological insights and practical guidelines for reservoir engineering, offering a framework to preserve quantum resources in high‐dimensional hybrid architectures.
Experimentalists seeking to improve the coherent lifetimes of quantum bits have generally focused on improvements to qubit designs, materials, and system isolation from environmental perturbations. In the case of the phase degree of freedom in a quantum superposition, however, the coherence that must be preserved is ultimately that of the qubit relative to the system clock, rather than that of the qubit in isolation. In this manuscript we clarify the impact of clock instability on qubit dephasing and provide quantitative estimates of fidelity upper-bounds set by noisy phase fluctuations in the clock. We first indicate analytically that such phase fluctuations in the clock - typically referred to as the local oscillator (LO) - are indistinguishable from a pure dephasing field arising from other environmental mechanisms. Using these results, we apply commonly quoted LO phase-noise specifications to calculate the resultant performance bounds on qubit operational fidelities. We find that laboratory grade LOs contribute error probabilities beyond 10−410^{-4}10−4 for operation times <1  μ<1\;\mu<1μs, while the use of precision LOs can suppress error rates by 10410^{4}104. We find that in either case phase fluctuations at frequencies far from the carrier dominate operational error rates, and due to their high-frequency spectral content, are difficult to mitigate using dynamic error suppression strategies. Further, we consider the importance of LO noise bandwidth and its impact on the degree to which thermal phase fluctuations in the LO contribute an effective error floor. These observations and analysis of the flow-down effects of such errors on the implementation of benchmarking and quantum error correction protocols highlight challenges and advantages that particular qubit technologies possess in the context of phase-noise-induced errors and motivate enhanced research in precision frequency metrology.
Abstract This research investigates the dynamics of entanglement and uncertainty‐induced nonlocality (UIN) in a spin‐1/2 Ising‐Heisenberg diamond chain subjected to local non‐Markovian decoherence channels. By examining amplitude damping (AD) and random telegraph noise (RTN) in both zero and finite temperature regimes, the study reveals nuanced distinctions in the degradation and revival of quantum correlations. The interplay between intrinsic spin couplings, thermal effects, and memory‐induced coherence backflow highlights the complex behavior of quantum resources under realistic noise conditions. Concurrence emerges as a sensitive marker of entanglement recovery in dephasing environments, while uncertainty‐induced nonlocality proves more resilient in high‐temperature or dissipative regimes. The analysis further demonstrates that moderate thermal activation and external magnetic fields can nontrivially enhance or suppress quantum features depending on system parameters. These findings offer a detailed perspective on the robustness and complementarity of different quantum correlation measures, providing guiding principles for the design of thermally stable and noise‐resilient quantum information protocols.