Dr Stavros Mouslopoulos

Research Interests: Symmetry, Coherence, and the Physics of Emergence

Richard Feynman once pointed to a strange asymmetry in physics. In geology, biology and cosmology, we naturally ask historical questions: how did the Earth evolve, how did species evolve, how did large-scale structure evolve? Physics, however, often begins by saying: here are the laws. But how did they get that way? How do the effective laws, phases, particles, classical states and measurement records we use every day emerge from deeper microscopic descriptions?

That question lies at the centre of my research.

My work spans theoretical physics, from high-energy models of modified gravity and multibrane worlds to current work in mesoscopic quantum many-body physics, open quantum systems and the foundations of quantum mechanics. The unifying theme is the physics of emergence: how large-scale effective behaviour arises from symmetry, tunnelling, degeneracy, localization, measurement and collective dynamics.

Current research: mesoscopic quantum physics and the quantum-to-classical transition

My recent work focuses on the Lipkin-Meshkov-Glick (LMG) model, a paradigmatic collective-spin system with a broken discrete (Z_2) symmetry. The model provides a controlled setting in which to study how quantum coherence survives, hides, decays or reappears in systems that are large enough to look classical but still small enough to retain quantum structure.

A central question is: under what precise conditions can a collective quantum system exhibit signatures of coherence that are irreducibly non-classical, and how do those signatures degrade under realistic environmental noise?

In Which Coherence Decoheres? Basis-Dependent Decoherence Rates in Symmetry-Broken Collective Spin Systems, I studied how decoherence depends on the basis in which coherence is defined. In a symmetry-broken collective spin system, coherence between energy eigenstates and coherence between localized pointer states do not decay at the same rate. The difference has a precise algebraic origin: parity symmetry removes the dominant dephasing cross-term in the energy basis. This gives a quantitative way to distinguish genuine quantum coherence from the classical relaxation of an order parameter.

In Classically Forbidden Signatures of Quantum Coherence in the Mesoscopic Lipkin-Meshkov-Glick Model, I examined the finite-size window in which macroscopic susceptibility and quantum coherence coexist. This “Goldilocks” regime allows strict Leggett-Garg inequality violations and Landau-Zener-type quantum-classical discriminators. The aim is to make the quantum-to-classical boundary experimentally testable, not merely philosophical.

In Reading Weakly, Acting Strongly: A Static Parity Horizon and its Dynamical Bypass in the Monitored Lipkin-Meshkov-Glick Model, I investigated the information-backaction structure of monitoring a symmetry-broken quantum system. A static magnetisation histogram can easily distinguish the two classical wells but remains almost blind to their relative parity. At the same time, the monitored operator can strongly disturb the hidden parity degree of freedom. I call this separation the static parity horizon. The paper then shows that a time-resolved measurement record can dynamically recover information that is invisible to a frozen classical snapshot.

Together, these papers form a developing research programme on symmetry-protected coherence, finite-size quantum dynamics, continuous measurement, and operational quantum-classical discrimination.

A forthcoming extension of this work is the sweep / Goldilocks programme. This project studies how the relevant signatures depend on system size, timestep, measurement strength and dephasing across a broad parameter space. The goal is to identify where quantum coherence is too microscopic to observe, where classicality has already washed it out, and where the experimentally useful mesoscopic window lies.

Earlier research: brane-world cosmology, massive gravity and emergence across scales

My current interest in symmetry breaking, tunnelling and emergent effective behaviour grew out of my earlier work in high-energy theoretical physics at the University of Oxford, followed by postdoctoral research at Los Alamos National Laboratory and Lawrence Berkeley National Laboratory.

In collaboration with Ian Kogan, Graham Ross, Antonios Papazoglou and others, I worked on multibrane worlds, multilocalization, radion physics, bulk fermions, bigravity, multigravity and modifications of gravity at large distances. This work included models in which effective mass scales and gravitational behaviour arise from higher-dimensional geometry and localization.

One central theme was the theoretical consistency of massive gravity. In particular, we showed how the van Dam-Veltman-Zakharov discontinuity can be circumvented in curved spacetime backgrounds such as de Sitter and anti-de Sitter space. We also developed bigravity and multigravity scenarios using positive-tension branes and studied how massive graviton modes and modified gravitational behaviour can emerge from extra-dimensional structure.

Although my current systems are collective spins rather than branes and gravitons, the conceptual architecture is continuous. In both settings, the key question is how an effective world emerges: a mass scale, a vacuum branch, a localized mode, a classical order parameter, a pointer state, or a measurement record.

Teaching and physics education

Alongside research, I am committed to making physics intellectually serious and accessible. I currently teach Physics and Mathematics at the University of Nottingham Ningbo China, where I co-convene Foundation Physics for a large engineering cohort. My teaching includes Foundation Physics and Foundation Calculus, with an emphasis on scaffolded problem solving, mathematical confidence, laboratory reasoning, modelling, units, uncertainty and the transition from school-level learning to university-level physics.

My teaching career has taken me through several international systems, including the UK, Australia, Switzerland, Mexico and China, and across curricula such as A-Levels, IB, AP and HSC. I hold a Diploma in Secondary School Education from the University of New South Wales and am currently completing a Postgraduate Certificate in Higher Education.

For me, teaching and research are not separate activities. Both are concerned with making hidden structure visible: in one case to the scientific community, in the other to students learning how to think physically.

Current keywords

Emergence; symmetry breaking; open quantum systems; decoherence; collective spin systems; Lipkin-Meshkov-Glick model; quantum-to-classical transition; Leggett-Garg inequalities; continuous measurement; parity horizon; finite-size scaling; spin-WKB methods; modified gravity; brane worlds; physics education.

I am a theoretical physicist and an accredited educator with a career spanning Europe, North America, Australia, and Asia. Holding dual Greek and Australian nationality, I have had the privilege of bringing a broad, international perspective to both my scientific research and my approach to physics education.

My academic journey began at the University of Ioannina, Greece, where I earned my Bachelor of Science in Physics with high distinction. I then moved to the University of Oxford to complete my PhD in Theoretical Physics. Under the supervision of Professors Graham G. Ross and Ian I. Kogan, my early research focused on high-energy particle physics, specifically string-theory-inspired brane-world scenarios and the modification of gravity at large scales. A notable breakthrough during this time was demonstrating how to circumvent the van Dam-Veltman-Zakharov (vDVZ) discontinuity in the graviton propagator by incorporating spacetime curvature. This foundational work led to postdoctoral research appointments at Los Alamos National Laboratory and Lawrence Berkeley National Laboratory in the United States.

Today, my research lies at the intersection of mesoscopic quantum many-body physics, open quantum systems, and the foundations of quantum mechanics. Unified by a deep interest in the physics of emergence, I investigate how robust classical-like behavior and macroscopic phenomena arise from an underlying unitary quantum substrate. In my recent publications, I utilize the exactly solvable Lipkin-Meshkov-Glick (LMG) model to explore basis-dependent decoherence rates in symmetry-broken phases and to establish rigorous, level-by-level dephasing thresholds for Leggett-Garg inequality violations. These insights provide falsifiable quantum-classical discriminators with direct applications to quantum metrology and spin squeezing.

Alongside my active research, I am committed to making the complexities of physics accessible to the next generation. Driven by this passion, I formalized my pedagogical training by earning a Diploma in Secondary School Education from the University of New South Wales (UNSW) in Sydney, becoming a fully accredited teacher in Australia. I am currently further enhancing my teaching practice by completing a Postgraduate Certificate in Higher Education (PGCHE).

My teaching career reflects my adaptability and a broad familiarity with global curricula. I have had the opportunity to teach in the United Kingdom, Switzerland, Mexico, Australia, and China, in diverse settings including Kaplan International College London, ONCAMPUS at the University of Southampton, the Immerse Education program at the University of Cambridge, and the Swiss Semester in Zermatt. Through this work, I have developed hands-on expertise with various educational frameworks, including UK A-Levels, the International Baccalaureate (IB), US AP courses, and the Australian HSC.

As an educator, I believe in taking a holistic approach to student development. I frequently extend my teaching beyond the standard curriculum by coaching students for Physics and Math Olympiads, leading STEM challenge clubs, mentoring university applicants, and serving as an Outdoor Education Leader. 

This semester, I am teaching Foundation Physics and Foundation Calculus at the University of Nottingham Ningbo China. These courses are designed to bridge the gap between high school and university-level rigor, using scaffolded problem-solving techniques to build deep conceptual understanding.

Foundation Physics (FP039) – Fall 2025: A fast-paced, calculus-exposed introduction to classical mechanics, electromagnetism, and fluids for students entering engineering or physical science degrees at UNNC. The course teaches with advanced mathematical formalism, including vector integrals, but assesses with algebra. Modern physics, gravitation, and thermodynamics are omitted to focus on helping students acclimate to university-level pace and notation. This course is required for FoSE progression.

Foundation Calculus (CELEN037) – Spring 2026: A rigorous, application-driven introduction to differential and integral calculus for students entering engineering, physical sciences, or economics. Focuses on mastery of core techniques—limits, derivatives, integrals, and series—with an emphasis on modeling and problem-solving. Prepares students for the mathematical demands of university-level coursework with a balance of theory and practical computation. Required for STEM degree progression.