The 8th International Conference on Matter and Radiation at Extremes (ICMRE2025)

187 / 2025-03-19 01:59:20

An Extreme Periodic Many-body Quantum Matter in an Ultra-cold Quantum Degenerate Plasma: Direct Observation of Fractional Elementary Charges

Extreme Quantum Matter, Topological Body, Quantum Degenerate Plasma, Fractional Quantum Hall Effect

An Extreme Periodic Many-body Quantum Matter in an Ultra-cold Quantum Degenerate Plasma: Direct Observation of Fractional Elementary Charges

Klaus Müller-Dethlefs

Emeritus Chair Professor of Physics and Chemistry, Founding Director of the Photon Science Institute

School of Natural Sciences, The University of Manchester, Manchester M13 9PL, UK

Emeritus Distinguished Professor and High-level Foreign Expert, School of Physics

Xi’an Jiaotong University, School of Science, Xi’an, Peoples Republic of China

k.muller-dethlefs@manchester.ac.uk

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We report the experimental observation of a very striking periodicity in a many-body system--an ultra-cold plasma. A long life-time (>0.3 ms) quantum degenerate molecular Rydberg plasma is generated in the high-density region of a pulsed supersonic jet expansion by two-colour resonant excitation of nitric oxide (10%) in neon (5bar) into the high-n Rydberg threshold region close to the ionization limit. Experimentally, two synchronous UV laser pulses produce the plasma a few mm away from the jet nozzle. For plasma densities of > 10¹⁶ cm^–3 reached in our experiments the electrons should become quantum degenerate, i.e. the electron de Broglie wavelength becomes larger than the Wigner-Seitz radius a relevant to describe the mean distance between the particles.

A time-of-flight (ToF) mass spectrometer collinearly with the jet expansion is used to analyse the plasma by applying two successive high-voltage pulses of 3.6 kV with a 0.2