This chapter explains the basic concept of decoherence and how it damps out quantum interference of a superposition state. Quantum decoherence plays an important role in the interpretation of quantum mechanics. The quantum information processing fields like quantum computers, quantum communication and quantum cryptography depend very much on how to minimize and control the quantum decoherence. Quantum decoherence helps to know the fundamental reasons of understanding the very nature of quantum mechanics, the measurement process and the boundary between quantum and classical behaviour. A double-slit experiment can be used to explain the basic concept of decoherence. The chapter discusses the master equations which give the dynamical evolution of the quantum system and the environment entangled state. It also discusses some of the decoherence models. In the collisional decoherence model, a massive free quantum particle scatters environmental particles. In the spin-boson models, the quantum system is represented by qubits and the environment by collision of harmonic oscillators.
This chapter explains the basic concept of decoherence and how it damps out quantum interference of a superposition state. Quantum decoherence plays an important role in the interpretation of quantum mechanics. The quantum information processing fields like quantum computers, quantum communication and quantum cryptography depend very much on how to minimize and control the quantum decoherence. Quantum decoherence helps to know the fundamental reasons of understanding the very nature of quantum mechanics, the measurement process and the boundary between quantum and classical behaviour. A double-slit experiment can be used to explain the basic concept of decoherence. The chapter discusses the master equations which give the dynamical evolution of the quantum system and the environment entangled state. It also discusses some of the decoherence models. In the collisional decoherence model, a massive free quantum particle scatters environmental particles. In the spin-boson models, the quantum system is represented by qubits and the environment by collision of harmonic oscillators.
Quantum decoherence is widely regarded as the principal dynamical mechanism through which classical behaviour emerges from quantum dynamics. This review presents a technical account of decoherence as an open-system phenomenon, emphasizing its mathematical framework, microscopic models, experimental evidence, and foundational implications. Starting from system-environment interactions and reduced density operators, we introduce completely positive trace-preserving maps and Lindblad master equations. We then discuss pure dephasing, pointer-state selection, quantum Brownian motion, spin-boson dynamics, and collisional decoherence. Experimental evidence from atom and molecular interferometry, superconducting qubits, and mesoscopic platforms is examined. Finally, the review assesses the role of decoherence in the quantum measurement problem. Decoherence explains preferred-basis selection and practical suppression of interference, but it does not independently account for the occurrence of a unique measurement outcome.
Quantum computing promises revolutionary advancements across various fields, but its practical realization is fundamentally limited by the phenomenon of quantum decoherence. Decoherence refers to the loss of quantum superposition and entanglement due to interactions with the surrounding environment, leading to computational errors. This paper presents a comprehensive modeling and prediction framework for quantum decoherence, aiming to provide a deeper understanding of this critical process. The framework utilizes a mathematically rigorous approach based on the principles of quantum mechanics, specifically focusing on the master equation formulation of decoherence. We derive a set of equations that accurately describe the evolution of the quantum state under the influence of various environmental noise sources. Furthermore, we explore methods for estimating decoherence rates and predicting the decoherence time, which is a crucial parameter for assessing the viability of quantum computations. The model incorporates key concepts such as the Bloch sphere representation, the Lindblad master equation, and the concept of decoherence channels. We demonstrate the applicability of the model to various quantum systems and discuss the potential for developing effective decoherence mitigation strategies. The ultimate goal is to provide a tool that can guide the design and optimization of quantum computers, ultimately paving the way for robust and reliable quantum computation.
We show that it is possible to explain the quantum measurement process within the framework of quantum mechanics without any additional postulates. The key concept of the theory is decoherence, which appears as an inherent characteristic of quantum mechanics and results from the uncertainty relation. In contrast to environment-induced decoherence, this decoherence exists prior to a measurement being made. To clarify our idea, we examine three elemental experiments: a Stern-Gerlach-like experiment, the Einstein-Podolsky-Rosen-Bohm (EPR-Bohm) experiment, and the double-slit experiment. By considering the first experiment, we explain how the uncertainty relation between position and momentum introduces decoherence prior to measurement. Consideration of the EPR-Bohm experiment leads us to conclude that the correlation of the EPR pair is not a consequence of what is known as the collapse of the wave function. Our theory of decoherence can also be applied to experiments with continuous eigenvalues, such as the double-slit experiment. Consideration of the double-slit experiment leads us to understand how pure quantum mechanics describes the fact that quanta behave as interfering particles.
This chapter introduces quantum mechanics through the experimental discoveries that revealed the limits of classical physics. Beginning with the historical debate over whether light is a wave or a particle, it examines Young’s double-slit experiment and its modern single-particle versions, which demonstrate that quantum objects can exist in superpositions of mutually exclusive states. The chapter explains how interference arises when alternative possibilities are not measured and how interaction with the environment suppresses these effects through decoherence, giving rise to classical behavior at macroscopic scales. A sequence of thought experiments involving interferometers and Stern–Gerlach devices highlights the counterintuitive structure of quantum measurement and the incompatibility of certain physical properties, as captured by the uncertainty principle. The chapter emphasizes that quantum mechanics does not describe particles taking multiple paths simultaneously in a classical sense but rather requires a new framework for probability based on amplitudes and interference. Finally, the discussion connects these foundational ideas to emerging technologies such as quantum computing, showing how superposition and entanglement can be harnessed to perform computations that have no classical analogue.
We show that it is possible to explain the quantum measurement process within the framework of quantum mechanics without any additional postulates. The key concept of the theory is decoherence, which appears as an inherent characteristic of quantum mechanics and results from the uncertainty relation. In contrast to environment-induced decoherence, this decoherence exists prior to a measurement being made. To clarify our idea, we examine three elemental experiments: a Stern-Gerlach-like experiment, the Einstein-Podolsky-Rosen-Bohm (EPR-Bohm) experiment, and the double-slit experiment. By considering the first experiment, we explain how the uncertainty relation between position and momentum introduces decoherence prior to measurement. Consideration of the EPR-Bohm experiment leads us to conclude that the correlation of the EPR pair is not a consequence of what is known as the collapse of the wave function. Our theory of decoherence can also be applied to experiments with continuous eigenvalues, such as the double-slit experiment. Consideration of the double-slit experiment leads us to understand how pure quantum mechanics describes the fact that quanta behave as interfering particles.
We show that it is possible to explain the quantum measurement process within the framework of quantum mechanics without any additional postulates. The key concept of the theory is decoherence, which appears as an inherent characteristic of quantum mechanics and results from the uncertainty relation. In contrast to environment-induced decoherence, this decoherence exists prior to a measurement being made. To clarify our idea, we examine three elemental experiments: a Stern-Gerlach-like experiment, the Einstein-Podolsky-Rosen-Bohm (EPR-Bohm) experiment, and the double-slit experiment. By considering the first experiment, we explain how the uncertainty relation between position and momentum introduces decoherence prior to measurement. Consideration of the EPR-Bohm experiment leads us to conclude that the correlation of the EPR pair is not a consequence of what is known as the collapse of the wave function. Our theory of decoherence can also be applied to experiments with continuous eigenvalues, such as the double-slit experiment. Consideration of the double-slit experiment leads us to understand how pure quantum mechanics describes the fact that quanta behave as interfering particles.