A superconductor to superfluid phase transition in liquid metallic hydrogen

TL;DR

This paper analyzes the quantum phases of liquid metallic hydrogen, predicting it may exhibit multiple ordered states such as superconductivity and superfluidity under magnetic fields, representing a new type of quantum fluid.

Contribution

It introduces a topological analysis predicting liquid metallic hydrogen can host multiple quantum ordered phases, unlike traditional single-phase categorization.

Findings

Liquid metallic hydrogen may transition between superconducting and superfluid states.

It cannot be classified solely as a superconductor or superfluid.

Multiple phase transitions are predicted under magnetic fields.

Abstract

Although hydrogen is the simplest of atoms, it does not form the simplest of solids or liquids. Quantum effects in these phases are considerable (a consequence of the light proton mass) and they have a demonstrable and often puzzling influence on many physical properties, including spatial order. To date, the structure of dense hydrogen remains experimentally elusive. Recent studies of the melting curve of hydrogen indicate that at high (but experimentally accessible) pressures, compressed hydrogen will adopt a liquid state, even at low temperatures. In reaching this phase, hydrogen is also projected to pass through an insulator-to-metal transition. This raises the possibility of new state of matter: a near ground-state liquid metal, and its ordered states in the quantum domain. Ordered quantum fluids are traditionally categorized as superconductors or superfluids; these respective systems feature dissipationless electrical currents or mass flow. Here we report an analysis based on topological arguments of the projected phase of liquid metallic hydrogen, finding that it may represent a new type of ordered quantum fluid. Specifically, we show that liquid metallic hydrogen cannot be categorized exclusively as a superconductor or superfluid. We predict that, in the presence of a magnetic field, liquid metallic hydrogen will exhibit several phase transitions to ordered states, ranging from superconductors to superfluids.