Black Holes, Lifshitz Spacetime and Decoherence in Quantum Field Theory.

Research demonstrates decoherence – the loss of quantum superposition – in field theories linked to gravity via the holographic principle. A moving mirror experiment reveals constant decoherence at finite temperature due to black holes, contrasting with power-law decay in zero-temperature Lifshitz spacetime, and highlights causality’s role in entangled particle decoherence.

The fundamental principles of quantum mechanics dictate that isolated systems evolve predictably, yet interaction with the environment invariably introduces decoherence – the loss of quantum superposition and entanglement. Recent research explores how gravity, specifically through the presence of black holes, influences this process. Kawamoto, Lee, and Yeh, in their paper ‘Decoherence by black holes via holography’, investigate decoherence effects within the framework of the holographic principle – a conjecture suggesting gravity in a volume can be described by a quantum field theory on its boundary. By modelling interactions between a quantum system and a field influenced by a Lifshitz black hole – a theoretical spacetime exhibiting scale invariance – the researchers demonstrate a constant rate of decoherence at finite temperatures, contrasting with a power-law decay observed in the absence of thermal effects. Their analysis, utilising a moving mirror thought experiment and entangled particle pairs, further highlights the role of causality in mediating decoherence within such systems.

Holographic Analysis Reveals Decoherence Dynamics in Strongly Coupled Systems

Decoherence, the process by which quantum superposition and entanglement give way to classical behaviour, continues to pose a significant challenge to fundamental physics and the development of quantum technologies. Recent research employs a holographic framework, based on the anti-de Sitter/conformal field theory (AdS/CFT) correspondence, to calculate decoherence rates and investigate the relationship between quantum information, gravity and quantum criticality.

The AdS/CFT correspondence is a theoretical ‘duality’ suggesting that a gravitational theory in a higher-dimensional anti-de Sitter (AdS) space is equivalent to a conformal field theory (CFT) on its boundary. This allows physicists to model strongly interacting quantum systems – where traditional perturbative calculations fail – using classical gravity in the higher-dimensional AdS space. The study utilises this approach, leveraging string theory and quantum gravity to model interactions between a quantum system and its environment.

Researchers constructed a simplified quantum system – a ‘moving mirror’ – interacting with quantum fields exhibiting quantum criticality. Quantum criticality refers to the behaviour of systems at the point where a phase transition occurs at zero temperature, exhibiting unusual fluctuations and correlations. Analysis focused on the ‘influence’ exerted by the environment, quantified through the dynamics of the moving mirror, and established a direct link between the geometry of the dual spacetime and the observed rate of decoherence in the boundary field theory.

Specifically, interactions with a finite temperature field, modelled using a Lifshitz black hole geometry – a solution to Einstein’s equations describing a spacetime with anisotropic scaling – consistently produced a constant rate of decoherence. This provides a quantitative measure of the environmental impact on the quantum system. Conversely, in the absence of thermal effects – represented by pure Lifshitz spacetime – decoherence decayed following a power-law at extended timescales, and ultimately vanished. This highlights the crucial role of thermal fluctuations in driving decoherence. The power-law decay observed in this zero-temperature regime mirrors patterns observed near extremal black holes – black holes with minimal charge-to-mass ratio – suggesting a universal mechanism governing decoherence in extreme gravitational environments.

The research also investigated the role of quantum entanglement in mitigating decoherence. The study demonstrated that decoherence experienced by one entangled particle does not necessarily translate to equivalent decoherence in its partner, due to the non-local correlations inherent in entanglement. This suggests that entanglement can, under certain conditions, act as a resource to preserve quantum coherence, offering a potential pathway for developing more robust quantum technologies.

These findings refine our understanding of decoherence processes, particularly in strongly coupled systems. The holographic approach provides a powerful tool for modelling and analysing decoherence, offering insights into the interplay between quantum information, gravity, and quantum criticality, and potentially informing future investigations into the foundations of quantum mechanics and the development of robust quantum technologies.