# Quantum-to-Classical Vortex Flow: Quantum Field Theory Dynamics in Rotating Curved Spacetimes

Gravity simulators are laboratory systems where small excitations like sound or surface waves behave as fields propagating on a curved spacetime geometry. The analogy between gravity and fluids requires vanishing viscosity, a feature naturally realised in superfluids like liquid helium or cold atomic clouds. In particular, quantum simulations of rotating curved spacetimes indicative of astrophysical black holes require the realisation of an extensive vortex flow in superfluid systems. Despite the inherent instability of multiply quantised vortices, we demonstrate that a stationary giant quantum vortex can be stabilised in superfluid 4He. Its compact core carries thousands of circulation quanta, prevailing over current limitations in other physical systems. We introduce a minimally invasive way to characterise the vortex flow by exploiting the interaction of micrometre-scale waves on the superfluid interface with the background velocity field. Intricate wave-vortex interactions, including the detection of bound states and distinctive analogue black hole ringdown signatures, have been observed. These results open new avenues to explore quantum-to-classical vortex transitions and utilise superfluid helium as a finite temperature quantum field theory simulator for rotating curved spacetimes.

# Early Universe Cosmology in the Lab

Many cosmologists believe that in the tiny fraction of a second following its birth, the Universe may have undergone one on more phase transitions as it cooled down and settled into a new state. I spoke with researchers Dalila Pirvu, Jonathan Braden and Alex Jenkins from QSimFP (Quantum Simulators for Fundamental Physics) to find out more about these fascinating processes and what we can hope to learn by replicating them in the laboratory.

# How can artists and scientists collaborate? - Conrad Shawcross

Conrad Shawcross is a London-based artist and one of the youngest members of the Royal Academy of Arts. Renowned for his scientific approach to his craft, Conrad draws on physical concepts such as geometry and interference to create unique spectacles, such as his Manifolds, Fracture and Patterns of Absence series.

Recently, Conrad has teamed up with QSimFP (Quantum Simulators for Fundamental Physics) to produce a collection of work for an Arts-Science exhibition, which will be held at Lakeside Arts (University of Nottingham) in 2025. The ambition of the collaboration is to sculpt the network's research on analogue simulation of quantum black holes and the early universe into a visually appealing and question provoking form that the general public can engage with.

In this video, Conrad talks about the benefits for two-way discourse between science and the arts, explaining how each of the these traditionally opposing disciplines has something to offer the other.

# An interview with Bill Unruh - Part V: Analogue experiments

Bill Unruh is a pre-eminent physicist working at the University of British Columbia. Perhaps best known for his discovery of the "Unruh effect", Bill has made seminal contributions to our understanding of gravity, black holes, quantum field theory in curved spacetime and the foundations of quantum mechanics. In this final clip, Bill tells us about a recent proposal to detect the Unruh effect in an analogue experiment.

# An interview with Bill Unruh - Part IV: Analogue Gravity

Bill Unruh is a pre-eminent physicist working at the University of British Columbia. Perhaps best known for his discovery of the "Unruh effect", Bill has made seminal contributions to our understanding of gravity, black holes, quantum field theory in curved spacetime and the foundations of quantum mechanics. In this video, Bill talks about his idea to test Hawking's prediction of black hole radiation using sound waves in a moving fluid, which ultimately developed into a new field of research called analogue gravity.

# An interview with Bill Unruh - Part III: The Unruh effect

Bill Unruh is a pre-eminent physicist working at the University of British Columbia. Perhaps best known for his discovery of the "Unruh effect", Bill has made seminal contributions to our understanding of gravity, black holes, quantum field theory in curved spacetime and the foundations of quantum mechanics. In this video, Bill gives us an explanation of the effect that bears his name: the Unruh effect.

# An interview with Bill Unruh - Part II: Black holes and the Hawking effect

Bill Unruh is a pre-eminent physicist working at the University of British Columbia. Perhaps best known for his discovery of the "Unruh effect", Bill has made seminal contributions to our understanding of gravity, black holes, quantum field theory in curved spacetime and the foundations of quantum mechanics. In this video, Bill explains how he started working on the problem of black hole evaporation around the time that Stephen Hawking made his famous discovery that black holes emit thermal radiation.

# An interview with Bill Unruh - Part I: Early Career

Bill Unruh is a pre-eminent physicist working at the University of British Columbia. Perhaps best known for his discovery of the "Unruh effect", Bill has made seminal contributions to our understanding of gravity, black holes, quantum field theory in curved spacetime and the foundations of quantum mechanics. In this video, Bill tells us about how he got interested in science, and shares some stories from time as a graduate student.