This work introduces SPQT (Stillness–Periphery Quantum Theory), an operational framework for parameterizing uncertainty relations in open quantum systems. Rather than treating quantum uncertainty as purely fundamental, SPQT characterizes how observable uncertainties scale with two measurable system properties: - Stillness (S): the purity or coherence of the quantum state- Periphery (Γ): environmental interaction strength and decoherence Using these quantities, we define an effective operational scale:ℏ_eff = ℏ(1 + λΓ/S) and derive a phenomenological uncertainty relation applicable to Gaussian and weakly perturbed states. The paper provides three complementary derivations:1. Diffusion of Gaussian wavepackets2. Steady-state variances from Lindblad dynamics3. Purity–covariance relations for Gaussian states SPQT recovers standard Heisenberg uncertainty for pure, isolated systems (S=1, Γ=0) and predicts measurable variance increases in realistic environments including cold atoms, trapped ions, cavity QED, and superconducting circuits. This framework offers a compact, experimentally testable parameterization of how decoherence and mixedness modify observable quantum uncertainties, while preserving the fundamental commutation relation [x,p]=iℏ. Note: SPQT is a phenomenological reframing of known open quantum system effects, presented as an alternative operational perspective rather than a fundamental extension of quantum mechanics. The parameter λ is phenomenological and must be determined from microscopic models or fitted to experimental data.
This work introduces SPQT (Stillness–Periphery Quantum Theory), an operational framework for parameterizing uncertainty relations in open quantum systems. Rather than treating quantum uncertainty as purely fundamental, SPQT characterizes how observable uncertainties scale with two measurable system properties: - Stillness (S): the purity or coherence of the quantum state- Periphery (Γ): environmental interaction strength and decoherence Using these quantities, we define an effective operational scale:ℏ_eff = ℏ(1 + λΓ/S) and derive a phenomenological uncertainty relation applicable to Gaussian and weakly perturbed states. The paper provides three complementary derivations:1. Diffusion of Gaussian wavepackets2. Steady-state variances from Lindblad dynamics3. Purity–covariance relations for Gaussian states SPQT recovers standard Heisenberg uncertainty for pure, isolated systems (S=1, Γ=0) and predicts measurable variance increases in realistic environments including cold atoms, trapped ions, cavity QED, and superconducting circuits. This framework offers a compact, experimentally testable parameterization of how decoherence and mixedness modify observable quantum uncertainties, while preserving the fundamental commutation relation [x,p]=iℏ. Note: SPQT is a phenomenological reframing of known open quantum system effects, presented as an alternative operational perspective rather than a fundamental extension of quantum mechanics. The parameter λ is phenomenological and must be determined from microscopic models or fitted to experimental data.
This paper introduces a phenomenological model for non-thermal decoherence in quantum devices based on an effective environmental “trace” parameter that captures local density and mechanical structure. We show that mass distribution, rigidity, and geometry can contribute additively to a device’s decoherence rate, independent of temperature. The framework explains several observed features in superconducting and trapped-ion platforms, including temperature plateaus, geometry sensitivity, and coherence variations linked to mechanical layout. The paper provides five falsifiable predictions and immediate engineering guidelines for improving coherence in current quantum hardware. The model requires no modification of quantum mechanics and is fully compatible with standard open-system theory. Includes manuscript and source files.
The challenge of making nano-scale quantum systems experimentally accessible is being overcome for an increasing diversity of systems by improved fabrication techniques and experimental control. Despite rapid progress, one of the main hindrances in all experiments is the difficulty of isolating the quantum system from the surrounding environment and its fluctuations. This experimental “noise” perturbs the quantum system, a process that is generally referred to as decoherence: the system slowly loses its distinguishing quantum features. In this thesis the effects of spatial correlations in the noise environment with a finite correlation length are investigated. The consequences for the experimental design of controlled quantum systems as well as the dynamics of solid state systems are presented. We utilize the Bloch-Redfield formalism, a Markovian master equation approach, which gives a close connection to the underpinning system-environment model. We show how to use this formalism to model any spatial correlation function of the noise environment. Using microscopic environmental models, several correlation functions are derived and their properties connected to the environmental parameters. Several phenomenological correlation functions are also studied and a mapping to the Lindblad master equation is presented, which provides a test of positivity for phenomenological models. For quantum transport through spin chains and networks, noise is generally detrimental. Spatial correlations however reduce the effect of dephasing noise and can reinstate the transport dynamics. The critical correlation length proves to be closely connected to the maximal packet width of one excitation in the transfer process. For dissipation noise, relaxation-free states emerge with spatial correlations. The decay of an excitation is therefore fundamentally modified into a fast decay towards an intermediate relaxation-reduced state and a subsequent decay to the ground state on a much longer time scale. In quantum metrology noise correlations have been observed in experiments with trapped ions, in which they limit the use of such experiments for metrology. Quantum advantage, i.e. a better precision scaling than the standard quantum limit has been proven impossible in the presence of uncorrelated Markovian noise only. We show that for certain optimized states the best possible quantum advantage, Heisenberg scaling, can be achieved in the presence of noise with a finite spatial decay of correlations. We furthermore identify how dephasing effects change and a topology dependence arises in strength with increasing correlation length for entangled states in a general way. Biological photosynthetic complexes have recently been found to potentially include quantum coherent dynamics, particularly in the process of transmitting an exciton from the point of creation to the reaction centre. We show how the formalism of spatially correlated decoherence adapts to this significantly different energy regime. Typical effects of decoherence in this field are presented and we show how the light-harvesting efficiency is influenced by spatial correlations in the noise. This thesis highlights the fundamental relevance of noise correlations to several fields of quantum physics and the importance of the efficient and comprehensive modelling techniques presented.
Quantum decoherence represents a fundamental challenge in the development and application of quantum technologies. This paper investigates the theoretical foundations of quantum decoherence, moving beyond the traditional view of it as a simple, isolated process. We argue that decoherence is a complex phenomenon arising from the interplay of multiple physical mechanisms at various scales. The core of this work is the development of a multi-scale model that integrates microscopic quantum effects – such as displacement, impurities, and time evolution – with macroscopic decoherence effects related to circuit design and material selection. We propose a framework for analyzing and simulating decoherence, recognizing the need for a more comprehensive mathematical description. This paper lays the groundwork for future research aimed at refining our understanding of decoherence and ultimately improving the robustness of quantum systems. ---
Abstract Understanding thermalization and irreversibility in open quantum systems requires char-acterizing the competition between coherent unitary dynamics and dissipative environmen-tal interactions. In this work, we present a systematic numerical study of thermalization dynamics in a two-qubit open quantum system governed by a completely positive and trace-preserving Lindblad master equation. The coherent evolution rate is controlled by a real scaling parameter α multiplying the Hamiltonian commutator, while decoherence is indepen-dently controlled by a dephasing rate γ . Although such a scaling of coherent dynamics can be absorbed into a rescaling of time in isolated systems, it becomes physically meaningful in open systems where decoherence introduces an absolute timescale. We investigate how the relative strength of coherent evolution and decoherence influences observable dynamics, purity decay, entropy production, and thermalization times. Using robust local and two-site observables, we show that varying α at fixed γ produces distinct transient trajectories, even though all evolutions converge to the same steady state. We further define an operational thermalization time τ ( γ, α ) based on a purity threshold and map the resulting thermalization-time surface across a broad parameter range. Increasing α generally accelerates oscillatory dynamics and modifies the approach to equilibrium, leading to measurable shifts in thermalization times without altering asymptotic states. These findings provide a clear and physically consistent characterization of how Hamil-tonian strength and decoherence rate jointly determine thermalization behavior in open quantum systems. The framework offers a practical parameterization for numerical mod-eling and experimental studies of coherent–dissipative competition in quantum information processing, quantum control, and open-system dynamics.
The notion of measurement is of both foundational and instrumental significance in quantum mechanics, and coherence destroyed by measurements (decoherence) lies at the very heart of quantum to classical transition. Qualitative aspects of this spirit have been widely recognized and analyzed ever since the inception of quantum theory. However, axiomatic and quantitative investigations of coherence are attracting great interest only recently with several figures of merit for coherence introduced [Baumgratz, Cramer, and Plenio, Phys. Rev. Lett. 113, 140401 (2014)]. While these resource theoretic approaches have many appealing and intuitive features, they rely crucially on various notions of incoherent operations which are sophisticated, subtle, and not uniquely defined, as have been critically assessed [Chitambar and Gour, Phys. Rev. Lett. 117, 030401 (2016)]. In this paper, we elaborate on the idea that coherence and quantum uncertainty are dual viewpoints of the same quantum substrate, and address coherence quantification by identifying coherence of a state (with respect to a measurement) with quantum uncertainty of a measurement (with respect to a state). Consequently, coherence measures may be set into correspondence with measures of quantum uncertainty. In particular, we take average quantum Fisher information as a measure of quantum uncertainty, and introduce the corresponding measure of coherence, which is demonstrated to exhibit desirable properties. Implications for interpreting quantum purity as maximal coherence, and quantum discord as minimal coherence, are illustrated.
Directed Recoherence in Structured Non-Markovian Environments presents a rigorously defined operating regime of open quantum system dynamics in which environmental memory leads not to oscillatory revivals, but to directed, monotonic recoherence toward a long-lived metastable coherence plateau. The work introduces a minimal and physically standard two-bath pure-dephasing model composed of a broadband Markovian noise bath and a narrowband non-Markovian reference bath. Within this framework, a dimensionless recoherence parameter R = λ_R² / [ γ_N Γ (1 + (δ/Γ)² ) ] is shown to govern a sharp transition between ordinary decoherence and a directed recoherence regime. When R exceeds a threshold of order unity, the system exhibits a single coherence minimum followed by monotonic recoherence and a metastable phase-locked plateau over experimentally relevant timescales. Exact closed-form solutions for the coherence dynamics are derived, alongside falsifiable predictions including bounded phase deviation relative to the reference bath. Numerical simulations confirm the existence of a critical threshold and distinguish this regime from known non-Markovian revivals, decoherence-free subspaces, driven steady states, and many-body prethermalization. The manuscript reframes Self-Initiated Phase Re-Coherence (SIPR) not as a new physical principle, but as a previously under-characterized regime within standard quantum open-system theory. Potential experimental realizations are discussed for superconducting qubits with Purcell-filtered environments and trapped ions with engineered sidebands. A companion conceptual document explores the epistemic and interpretational implications of measurement, observation, and environmental structure without modifying the physical results presented here.