Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

Journal of Plasma Physics

Self-organization in the avalanche, quench and dissipation of a molecular ultracold plasma

Kevin L. Marroquin, Ruyang Wang, Amin Allahverdian, Nathan Durand-Brousseau, S. Colombini, Felix Kogel, James Keller, Tim Langen, Edward R. Grant

Published Jan 17, 2024• 3 citations
Publisher

Abstract

Spontaneous avalanche to plasma begins in the core of an ellipsoidal Rydberg gas of nitric oxide. Ambipolar expansion of NO $^+$ draws energy from avalanche-heated electrons. Then, cycles of long-range resonant electron transfer from Rydberg molecules to ions equalize their relative velocities. This sequence of steps gives rise to a remarkable mechanics of self-assembly, in which the kinetic energy of initially formed hot electrons and ions drives an observed separation of plasma volumes. These dynamics adiabatically sequester energy in a reservoir of mass transport, starting a process that anneals separating volumes to form an apparent glass of strongly coupled ions and electrons. Short-time electron spectroscopy provides experimental evidence for complete ionization. The long lifetime of this system, particularly its stability with respect to recombination and neutral dissociation, suggests that this transformation affords a robust state of arrested relaxation, far from thermal equilibrium. We see this most directly in the excitation spectrum of transitions to states in the initially selected Rydberg series, detected as the long-lived signal that survives a flight time of $500\ \mathrm {\mu }$ s to reach an imaging detector. The initial density of electrons produced by prompt Penning ionization, which varies with the selected initial principal quantum number and density of the Rydberg gas, determines a balance between the rising density of ions and the falling density of Rydberg molecules. This Penning-regulated ion-Rydberg molecule balance appears necessary as a critical factor in achieving the long ultracold plasma lifetime to produce spectral features detected after very long delays.

DOI
10.1017/s0022377823001472

Related papers

Arrested relaxation in an isolated molecular ultracold plasma

Rafael Haenel, Markus Schulz-Weiling, John Sous +5 more

Spontaneous avalanche to plasma splits the core of an ellipsoidal Rydberg gas of nitric oxide. Ambipolar expansion first quenches the electron temperature of this core plasma. Then, long-range, resonant charge transfer from ballistic ions to frozen Rydberg molecules in the wings of the ellipsoid quenches the ion-Rydberg-molecule relative velocity distribution. This sequence of steps gives rise to a remarkable mechanics of self-assembly, in which the kinetic energy of initially formed hot electrons and ions drives an observed separation of plasma volumes. These dynamics adiabatically sequester energy in a reservoir of mass transport, starting a process that anneals separating volumes to form an apparent glass of strongly coupled ions and electrons. Short-time electron spectroscopy provides experimental evidence for complete ionization. The long lifetime of this system, particularly its stability with respect to recombination and neutral dissociation, suggests that this transformation affords a robust state of arrested relaxation, far from thermal equilibrium.

arXiv:1703.01188•Physical Review A•Aug 15, 2017•21 citations

Dissipative dynamics of atomic and molecular Rydberg gases: Avalanche to ultracold plasma states of strong coupling

M. Aghigh, K. M. Grant, Rafael Haenel +8 more

Abstract Not long after metastable xenon was photoionized in a magneto-optical trap, groups in Europe and North America found that similar states of ionized gas evolved spontaneously from state-selected, high principal quantum number Rydberg gases. Studies of atomic xenon and molecular nitric oxide entrained in a supersonically cooled molecular beam subsequently showed much the same final state evolved from a sequence of prompt Penning ionization and electron-impact avalanche to plasma, well-described by coupled rate-equation simulations. But, measured over longer times, the molecular ultracold plasma was found to exhibit an anomalous combination of very long lifetime and very low apparent electron temperature. This review first summarizes early developments in the general study of ultracold plasmas formed by atomic and molecular Rydberg gases, and then turns to describe the particular properties of the nitric oxide molecular ultracold plasma that appear to call for an explanation beyond the realm of conventional plasma physics.

arXiv:1908.07633•Journal of Physics B Atomic Molecular and Optical Physics•Dec 11, 2019•13 citations

Quantum state control of ultracold plasma fission

Markus Schulz-Weiling, Edward R. Grant

Abstract Double-resonant transitions excite nitric oxide in a seeded supersonic molecular beam, yielding a state-selected Rydberg gas that evolves to form an ultracold plasma. This plasma propagates in z with the molecular beam over a variable distance as great as 600 mm to strike an imaging detector, which records the charge distribution in the dimensions, x and y . The laser-crossed molecular beam excitation geometry convolutes an axial Gaussian distribution of NO about z with the Gaussian intensity distribution of the laser beam about x to create an ellipsoidal volume of Rydberg gas. Plasma images provide evidence for the relaxation of this Rydberg gas volume in an electron impact avalanche that breaks the ellipsoidal symmetry in x to form repelling plasma volumes. We find that the energy deposited in the recoil velocity of mass transport, V x depends systematically on the initially selected Rydberg gas principal quantum number, n 0 , and the initial density of the Rydberg gas, ρ 0 . These quantities combine to determine ρ e , the initial density of electrons formed by the prompt Penning ionization of closely spaced pairs of Rydberg molecules. Above a threshold density of Penning electrons, we find that V x depends linearly on ρ e . We argue that this bifurcation occurs as a consequence of the initial geometry of the Rydberg gas. Ambipolar electron expansion accelerates initially formed core ions. Resonant charge transfer redistributes this ion energy to the column of Rydberg molecules on the long axis of the ellipsoid. The equalized velocities in each direction give rise to a ± x streaming motion that concentrates density in opposing plasma volumes, causing the symmetric gas volume to split like a rotating liquid drop. Significantly, these dynamics reduce electron temperature with little decrease in the ion density or increase in the ion temperature. This appears to facilitate the formation of a strongly coupled plasma.

Journal of Physics B Atomic Molecular and Optical Physics•Mar 7, 2016•11 citations

mm-wave Rydberg–Rydberg transitions gauge intermolecular coupling in a molecular ultracold plasma

Ruoxi Wang, John Sous, M. Aghigh +5 more

Out-of-equilibrium, strong correlation in a many-body system can trigger emergent properties that act to constrain the natural dissipation of energy and matter. Signs of such self-organization appear in the avalanche, bifurcation, and quench of a state-selected Rydberg gas of nitric oxide to form an ultracold, strongly correlated ultracold plasma. Work reported here focuses on the initial stages of avalanche and quench and uses the mm-wave spectroscopy of an embedded quantum probe to characterize the intermolecular interaction dynamics associated with the evolution to plasma. Double-resonance excitation prepares a Rydberg gas of nitric oxide composed of a single selected state of principal quantum number, n0. Penning ionization, followed by an avalanche of electron–Rydberg collisions, forms a plasma of NO+ ions and weakly bound electrons, in which a residual population of n0 Rydberg molecules evolves to a state of high orbital angular momentum, ℓ. Predissociation depletes the plasma of low-ℓ molecules. Relaxation ceases and n0ℓ(2) molecules with ℓ ≥ 4 persist for very long times. At short times, varying excitation spectra of mm-wave Rydberg–Rydberg transitions mark the rate of electron-collisional ℓ-mixing. Deep depletion resonances that persist for long times signal energy redistribution in the basis of central-field Rydberg states. The widths and asymmetries of Fano line shapes witness the degree to which coupling in the arrested bath (i) broadens the allowed transition and (ii) mixes the local network of levels in the ensemble.

arXiv:2005.10088•The Journal of Chemical Physics•May 4, 2022•3 citations

Ultracold molecular plasma

Markus Schulz-Weiling

The conditions aforded by a skimmed free-jet expansion intersected by two laser pulses, driving resonant transitions in nitric oxide, determine the phase-space volume of a dense molecular Rydberg ensemble. Spontaneous avalanche to plasma within this system leads to the development of two macroscopic domains. These domains are clearly distinguished by their polarizability as well as their locality within the plasma. The first domain appears at the system core, is polarized by fields exceeding 500 mV/cm and displays an ambipolar expansion character suggestive of initial electron temperatures exceeding 150 Kelvin. The second domain travels with the velocity of the supersonic beam and is robust to the application of several hundred V/cm pulses. It is further distinguished through the apparent arrest of relaxation channels, annealing the domain over a millisecond or more in a state far from thermal equilibrium. Both domains are linked via the spontaneous breaking of ellipsoidal symmetry to form bifurcating arrested volumes.

•Jan 1, 2017•0 citations

On the formation and decay of a molecular ultracold plasma

Nicolas Saquet, J. P. Morrison, Markus Schulz-Weiling +4 more

Double-resonant photoexcitation of nitric oxide in a molecular beam creates a dense ensemble of 50f(2) Rydberg states, which evolves to form a plasma of free electrons trapped in the potential well of an NO + space charge. The plasma travels at the velocity of the molecular beam and, on passing through a grounded grid, yields an electron time-of-flight signal that gauges the plasma size and quantity of trapped electrons. This plasma expands at a rate that fits with an electron temperature as low as 5 K, colder than typically observed for atomic ultracold plasmas. The recombination of molecular NO + cations with electrons forms neutral molecules excited by more than twice the energy of the NO chemical bond, and the question arises whether neutral fragmentation plays a role in shaping the redistribution of energy and particle density that directs the short-time evolution from Rydberg gas to plasma. To explore this question, we adapt a coupled rate-equations model established for atomic ultracold plasmas to describe the energy-grained avalanche of electron–Rydberg and electron–ion collisions in our system. Adding channels of Rydberg predissociation and two-body, electron–cation dissociative recombination to the atomic formalism, we investigate the kinetics by which this relaxation distributes particle density and energy over Rydberg states, free electrons and neutral fragments. The results of this investigation point to conditions under which such processes can effect the steady-state temperature of plasma electrons.

arXiv:1103.0053•Journal of Physics B Atomic Molecular and Optical Physics•Sep 14, 2011•27 citations
Spontaneous avalanche to plasma begins in the core of an ellipsoidal Rydberg gas of nitric oxide. Ambipolar expansion of NO +^++ draws energy from avalanche-heated electrons. Then, cycles of long-range resonant electron transfer from Rydberg molecules to ions equalize their relative velocities. This sequence of steps gives rise to a remarkable mechanics of self-assembly, in which the kinetic energy of initially formed hot electrons and ions drives an observed separation of plasma volumes. These dynamics adiabatically sequester energy in a reservoir of mass transport, starting a process that anneals separating volumes to form an apparent glass of strongly coupled ions and electrons. Short-time electron spectroscopy provides experimental evidence for complete ionization. The long lifetime of this system, particularly its stability with respect to recombination and neutral dissociation, suggests that this transformation affords a robust state of arrested relaxation, far from thermal equilibrium. We see this most directly in the excitation spectrum of transitions to states in the initially selected Rydberg series, detected as the long-lived signal that survives a flight time of 500 μ500\ \mathrm {\mu }500 μ s to reach an imaging detector. The initial density of electrons produced by prompt Penning ionization, which varies with the selected initial principal quantum number and density of the Rydberg gas, determines a balance between the rising density of ions and the falling density of Rydberg molecules. This Penning-regulated ion-Rydberg molecule balance appears necessary as a critical factor in achieving the long ultracold plasma lifetime to produce spectral features detected after very long delays.
Spontaneous avalanche to plasma splits the core of an ellipsoidal Rydberg gas of nitric oxide. Ambipolar expansion first quenches the electron temperature of this core plasma. Then, long-range, resonant charge transfer from ballistic ions to frozen Rydberg molecules in the wings of the ellipsoid quenches the ion-Rydberg-molecule relative velocity distribution. This sequence of steps gives rise to a remarkable mechanics of self-assembly, in which the kinetic energy of initially formed hot electrons and ions drives an observed separation of plasma volumes. These dynamics adiabatically sequester energy in a reservoir of mass transport, starting a process that anneals separating volumes to form an apparent glass of strongly coupled ions and electrons. Short-time electron spectroscopy provides experimental evidence for complete ionization. The long lifetime of this system, particularly its stability with respect to recombination and neutral dissociation, suggests that this transformation affords a robust state of arrested relaxation, far from thermal equilibrium.
Abstract Not long after metastable xenon was photoionized in a magneto-optical trap, groups in Europe and North America found that similar states of ionized gas evolved spontaneously from state-selected, high principal quantum number Rydberg gases. Studies of atomic xenon and molecular nitric oxide entrained in a supersonically cooled molecular beam subsequently showed much the same final state evolved from a sequence of prompt Penning ionization and electron-impact avalanche to plasma, well-described by coupled rate-equation simulations. But, measured over longer times, the molecular ultracold plasma was found to exhibit an anomalous combination of very long lifetime and very low apparent electron temperature. This review first summarizes early developments in the general study of ultracold plasmas formed by atomic and molecular Rydberg gases, and then turns to describe the particular properties of the nitric oxide molecular ultracold plasma that appear to call for an explanation beyond the realm of conventional plasma physics.
Abstract Double-resonant transitions excite nitric oxide in a seeded supersonic molecular beam, yielding a state-selected Rydberg gas that evolves to form an ultracold plasma. This plasma propagates in z with the molecular beam over a variable distance as great as 600 mm to strike an imaging detector, which records the charge distribution in the dimensions, x and y . The laser-crossed molecular beam excitation geometry convolutes an axial Gaussian distribution of NO about z with the Gaussian intensity distribution of the laser beam about x to create an ellipsoidal volume of Rydberg gas. Plasma images provide evidence for the relaxation of this Rydberg gas volume in an electron impact avalanche that breaks the ellipsoidal symmetry in x to form repelling plasma volumes. We find that the energy deposited in the recoil velocity of mass transport, V x depends systematically on the initially selected Rydberg gas principal quantum number, n 0 , and the initial density of the Rydberg gas, ρ 0 . These quantities combine to determine ρ e , the initial density of electrons formed by the prompt Penning ionization of closely spaced pairs of Rydberg molecules. Above a threshold density of Penning electrons, we find that V x depends linearly on ρ e . We argue that this bifurcation occurs as a consequence of the initial geometry of the Rydberg gas. Ambipolar electron expansion accelerates initially formed core ions. Resonant charge transfer redistributes this ion energy to the column of Rydberg molecules on the long axis of the ellipsoid. The equalized velocities in each direction give rise to a ± x streaming motion that concentrates density in opposing plasma volumes, causing the symmetric gas volume to split like a rotating liquid drop. Significantly, these dynamics reduce electron temperature with little decrease in the ion density or increase in the ion temperature. This appears to facilitate the formation of a strongly coupled plasma.
Out-of-equilibrium, strong correlation in a many-body system can trigger emergent properties that act to constrain the natural dissipation of energy and matter. Signs of such self-organization appear in the avalanche, bifurcation, and quench of a state-selected Rydberg gas of nitric oxide to form an ultracold, strongly correlated ultracold plasma. Work reported here focuses on the initial stages of avalanche and quench and uses the mm-wave spectroscopy of an embedded quantum probe to characterize the intermolecular interaction dynamics associated with the evolution to plasma. Double-resonance excitation prepares a Rydberg gas of nitric oxide composed of a single selected state of principal quantum number, n0. Penning ionization, followed by an avalanche of electron–Rydberg collisions, forms a plasma of NO+ ions and weakly bound electrons, in which a residual population of n0 Rydberg molecules evolves to a state of high orbital angular momentum, ℓ. Predissociation depletes the plasma of low-ℓ molecules. Relaxation ceases and n0ℓ(2) molecules with ℓ ≥ 4 persist for very long times. At short times, varying excitation spectra of mm-wave Rydberg–Rydberg transitions mark the rate of electron-collisional ℓ-mixing. Deep depletion resonances that persist for long times signal energy redistribution in the basis of central-field Rydberg states. The widths and asymmetries of Fano line shapes witness the degree to which coupling in the arrested bath (i) broadens the allowed transition and (ii) mixes the local network of levels in the ensemble.
The conditions aforded by a skimmed free-jet expansion intersected by two laser pulses, driving resonant transitions in nitric oxide, determine the phase-space volume of a dense molecular Rydberg ensemble. Spontaneous avalanche to plasma within this system leads to the development of two macroscopic domains. These domains are clearly distinguished by their polarizability as well as their locality within the plasma. The first domain appears at the system core, is polarized by fields exceeding 500 mV/cm and displays an ambipolar expansion character suggestive of initial electron temperatures exceeding 150 Kelvin. The second domain travels with the velocity of the supersonic beam and is robust to the application of several hundred V/cm pulses. It is further distinguished through the apparent arrest of relaxation channels, annealing the domain over a millisecond or more in a state far from thermal equilibrium. Both domains are linked via the spontaneous breaking of ellipsoidal symmetry to form bifurcating arrested volumes.
Double-resonant photoexcitation of nitric oxide in a molecular beam creates a dense ensemble of 50f(2) Rydberg states, which evolves to form a plasma of free electrons trapped in the potential well of an NO + space charge. The plasma travels at the velocity of the molecular beam and, on passing through a grounded grid, yields an electron time-of-flight signal that gauges the plasma size and quantity of trapped electrons. This plasma expands at a rate that fits with an electron temperature as low as 5 K, colder than typically observed for atomic ultracold plasmas. The recombination of molecular NO + cations with electrons forms neutral molecules excited by more than twice the energy of the NO chemical bond, and the question arises whether neutral fragmentation plays a role in shaping the redistribution of energy and particle density that directs the short-time evolution from Rydberg gas to plasma. To explore this question, we adapt a coupled rate-equations model established for atomic ultracold plasmas to describe the energy-grained avalanche of electron–Rydberg and electron–ion collisions in our system. Adding channels of Rydberg predissociation and two-body, electron–cation dissociative recombination to the atomic formalism, we investigate the kinetics by which this relaxation distributes particle density and energy over Rydberg states, free electrons and neutral fragments. The results of this investigation point to conditions under which such processes can effect the steady-state temperature of plasma electrons.