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

Physical Review Letters

Nuclear-spin waves in polarized atomic hydrogen gas: Temperature and density dependence in the hydrodynamic and Knudsen regimes

N. P. Bigelow, Jack H. Freed, D. M. Lee

Published Oct 9, 1989• 46 citations
Publisher

Abstract

Accurate measurements on the nuclear-spin waves observed in the NMR spectrum of spin-polarized atomic hydrogen provide a quantitative test of theory. Results for temperatures between 160 and 537 mK and densities between 7\ifmmode\times\else\texttimes\fi{}${10}^{15}$ and 5\ifmmode\times\else\texttimes\fi{}${10}^{16}$ ${\mathrm{cm}}^{\mathrm{\ensuremath{-}}3}$ display the expected magnitude and ${T}^{\mathrm{\ensuremath{-}}1/2}$ divergence predicted for the spin-wave quality factor \ensuremath{\mu}. It is shown that spin waves persist at low enough densities (Knudsen regime) that elastic wall collisions are more probable than atom-atom exchange collisions. An anomalous increase in spin-wave widths at low temperatures is explained in terms of the enhanced effects of sticking collisions of the atoms with the walls.

DOI
10.1103/physrevlett.63.1609

Related papers

Continuous-wave NMR in spin-polarized atomic hydrogen

S. Penttilä, Tapio O. Niinikoski, J.M. Rieubland +1 more

Simultaneous continuous-wave NMR and total-pressure measurements on spin-polarized atomic hydrogen gas in a 5-T magnetic field are reported. During sample loading we observe positive nuclear polarization. The rf susceptibility of the decaying sample is nonlinearly related to the density. This and the anomalous NMR line shape are discussed in light of the identical spin-rotation effect and the hydrodynamic spin-wave model. The analysis of the time evolution of the NMR signal area and of the pressure gives the two-body exchange recombination-rate coefficients ${K}_{\mathrm{aa}}$=1.8\ifmmode\times\else\texttimes\fi{}${10}^{\mathrm{\ensuremath{-}}19}$ ${\mathrm{cm}}^{3}$ ${\mathrm{s}}^{\mathrm{\ensuremath{-}}1}$ and ${K}_{\mathrm{ab}}$=1.6\ifmmode\times\else\texttimes\fi{}${10}^{\mathrm{\ensuremath{-}}19}$ ${\mathrm{cm}}^{3}$ ${\mathrm{s}}^{\mathrm{\ensuremath{-}}1}$, and the one-body relaxation rate ${G}_{1}$=1\ifmmode\times\else\texttimes\fi{}${10}^{\mathrm{\ensuremath{-}}4}$ ${\mathrm{s}}^{\mathrm{\ensuremath{-}}1}$ in the absence of rf field, at T=370 mK.

Physical review. B, Condensed matter•Sep 1, 1987•1 citation

Spin-polarized atomic hydrogen: A magnetic gas (invited)

Isaac F. Silvera, Jook T. M. Walraven

Atomic hydrogen (H) has recently been created in a long-lived state referred to as spin-polarized atomic hydrogen (H↓). A moderate density gas (n≃1017 atoms/ cc) has been produced at temperatures T≃400 mK. H↓ is predicted to be the only atomic substance that remains gaseous to T = 0 K; current experiments are consistent with this picture. Since the H↓ atoms behave as composite bosons the gas is expected to have a Bose-Einstein condensation (BEC) and related superfluidity at a sufficiently high density or low temperature. H↓ is expected to display spectacular static and dynamic properties. Since the gas is polarized, the dominant electronic magnetization, M⃗e, is proportional to the atomic density. In an inhomogeneous magnetic field M⃗e will also be highly inhomogeneous. BEC will be spatially localized and the static M⃗e should be an identifying feature of this state. The low-lying excitation spectrum should not only feature electronic and nuclear spin-transitions, but should also have magnetic translational modes of the gas. The experimental technique for stabilization of H↓ as well as many of the predicted magnetic properties are discussed.

Journal of Applied Physics•Mar 1, 1981•17 citations

Magnetic resonance line shifts in the quantum gas of atomic hydrogen

Janne Ahokas, Otto Vainio, S Novotny +2 more

We present an experimental study of the quantum gas of atomic hydrogen in a strong magnetic field (4.6 T). The gas is compressed to densities of ~1018 cm−3 at temperatures of 0.2–0.5 K. We observed shifts of the electron spin resonance (ESR) lines caused by the exchange interaction in atomic collisions (clock shift) and the long-range dipolar interactions. The clock shift was found to be vanishingly small in a doubly polarized gas, in contrast to a mixture of two hyperfine states. The difference is explained by properly including quantum statistical effects in the treatment of atomic collisions. From our data, we extract the difference between the triplet and singlet s-wave scattering lengths, at−as=60(10) pm, in agreement with existing theories. At densities above 1017 cm−3, weakly resolved structures appeared in the ESR spectra, interpreted in terms of electron spin waves. We consider exchange and dipolar interactions to possibly induce the spin waves.

Physica Scripta•Sep 1, 2010•0 citations

Magnetic trapping of spin-polarized atomic hydrogen

Harald F. Hess, Greg Kochanski, John M. Doyle +3 more

We have confined over 5\ifmmode\times\else\texttimes\fi{}${10}^{12}$ atoms of hydrogen in a static magnetic trap. The atoms are loaded into the trap by precooling with a dilution refrigerator. At operating densities near 1\ifmmode\times\else\texttimes\fi{}${10}^{13}$ ${\mathrm{cm}}^{\mathrm{\ensuremath{-}}3}$ the gas is observed to be electron and nuclear polarized in the uppermost hyperfine state. The long lifetime of the trapped gas (over 20 min) suggests that it is thermally decoupled from the wall and has evaporatively cooled to a temperature of about 40 mK. The residual decay of the gas density is consistent with spin relaxation induced by dipolar interactions between atoms.

Physical Review Letters•Aug 10, 1987•238 citations

Hyperfine and electronic spin waves in atomic hydrogen : the role of the spin exchange process

J. P. Bouchaud, C. Lhuillier

The identical spin rotation effect is the quantum mechanical collisional effect underlying the transverse nuclear spin waves recently seen in dilute non degenerate gases in Paris [3He] and at Cornell University [H↓]. This mechanism could in principle give rise, at low enough temperatures, to hydrodynamic oscillatory modes associated with any non diagonal elements of the atomic internal density matrix (generalized spin waves or coherences waves). Starting from a quantum Boltzmann equation recently derived for the study of 4-component atomic hydrogen, we show that the current of any transverse quantity (hyperfine or Zeeman coherence) does indeed precess around molecular exchange fields. Unhappily, in most cases, the oscillatory modes associated with these transverse quantities are heavily damped. The first intrinsic cause of damping of these waves is spin exchange. We study the conditions under which this damping is minimized in both zero field and in high magnetic field. Numerical values of all relevant parameters for the description of spin transport properties in atomic hydrogen are given in the appendices.

Journal de physique•Jan 1, 1985•7 citations

Identical spin rotation effect and electron spin waves in quantum gas of atomic hydrogen

L. Lehtonen, Otto Vainio, Janne Ahokas +7 more

We present an experimental study of electron spin waves in atomic hydrogen gas compressed to high densities of ∼5 × 10 18 cm −3 at temperatures ranging from 0.26 to 0.6 K in the strong magnetic field of 4.6 T. Hydrogen gas is in a quantum regime when the thermal de-Broglie wavelength is much larger than the s -wave scattering length. In this regime the identical particle effects play a major role in atomic collisions and lead to the identical spin rotation effect (ISR). We observed a variety of spin wave modes caused by this effect with strong dependence on the magnetic potential caused by variations of the polarizing magnetic field. We demonstrate confinement of the ISR modes in the magnetic potential and manipulate their properties by changing the spatial profile of the magnetic field. We have found that at a high enough density of H gas the magnons accumulate in their ground state in the magnetic trap and exhibit long coherence, which has a profound effect on the electron spin resonance spectra. Such macroscopic accumulation of the ground state occurs at a certain critical density of hydrogen gas, where the chemical potential of the magnons becomes equal to the energy of their ground state in the trapping potential.

arXiv:1609.08432•New Journal of Physics•May 4, 2018•2 citations
Accurate measurements on the nuclear-spin waves observed in the NMR spectrum of spin-polarized atomic hydrogen provide a quantitative test of theory. Results for temperatures between 160 and 537 mK and densities between 7\ifmmode\times\else\texttimes\fi{}1015{10}^{15}1015 and 5\ifmmode\times\else\texttimes\fi{}1016{10}^{16}1016 cm\ensuremath−3{\mathrm{cm}}^{\mathrm{\ensuremath{-}}3}cm\ensuremath−3 display the expected magnitude and T\ensuremath−1/2{T}^{\mathrm{\ensuremath{-}}1/2}T\ensuremath−1/2 divergence predicted for the spin-wave quality factor \ensuremath{\mu}. It is shown that spin waves persist at low enough densities (Knudsen regime) that elastic wall collisions are more probable than atom-atom exchange collisions. An anomalous increase in spin-wave widths at low temperatures is explained in terms of the enhanced effects of sticking collisions of the atoms with the walls.
Simultaneous continuous-wave NMR and total-pressure measurements on spin-polarized atomic hydrogen gas in a 5-T magnetic field are reported. During sample loading we observe positive nuclear polarization. The rf susceptibility of the decaying sample is nonlinearly related to the density. This and the anomalous NMR line shape are discussed in light of the identical spin-rotation effect and the hydrodynamic spin-wave model. The analysis of the time evolution of the NMR signal area and of the pressure gives the two-body exchange recombination-rate coefficients Kaa{K}_{\mathrm{aa}}Kaa​=1.8\ifmmode\times\else\texttimes\fi{}${10}^{\mathrm{\ensuremath{-}}19}$ cm3{\mathrm{cm}}^{3}cm3 ${\mathrm{s}}^{\mathrm{\ensuremath{-}}1}$ and Kab{K}_{\mathrm{ab}}Kab​=1.6\ifmmode\times\else\texttimes\fi{}${10}^{\mathrm{\ensuremath{-}}19}$ cm3{\mathrm{cm}}^{3}cm3 ${\mathrm{s}}^{\mathrm{\ensuremath{-}}1}$, and the one-body relaxation rate G1{G}_{1}G1​=1\ifmmode\times\else\texttimes\fi{}${10}^{\mathrm{\ensuremath{-}}4}$ ${\mathrm{s}}^{\mathrm{\ensuremath{-}}1}$ in the absence of rf field, at T=370 mK.
Atomic hydrogen (H) has recently been created in a long-lived state referred to as spin-polarized atomic hydrogen (H↓). A moderate density gas (n≃1017 atoms/ cc) has been produced at temperatures T≃400 mK. H↓ is predicted to be the only atomic substance that remains gaseous to T = 0 K; current experiments are consistent with this picture. Since the H↓ atoms behave as composite bosons the gas is expected to have a Bose-Einstein condensation (BEC) and related superfluidity at a sufficiently high density or low temperature. H↓ is expected to display spectacular static and dynamic properties. Since the gas is polarized, the dominant electronic magnetization, M⃗e, is proportional to the atomic density. In an inhomogeneous magnetic field M⃗e will also be highly inhomogeneous. BEC will be spatially localized and the static M⃗e should be an identifying feature of this state. The low-lying excitation spectrum should not only feature electronic and nuclear spin-transitions, but should also have magnetic translational modes of the gas. The experimental technique for stabilization of H↓ as well as many of the predicted magnetic properties are discussed.
We present an experimental study of the quantum gas of atomic hydrogen in a strong magnetic field (4.6 T). The gas is compressed to densities of ~1018 cm−3 at temperatures of 0.2–0.5 K. We observed shifts of the electron spin resonance (ESR) lines caused by the exchange interaction in atomic collisions (clock shift) and the long-range dipolar interactions. The clock shift was found to be vanishingly small in a doubly polarized gas, in contrast to a mixture of two hyperfine states. The difference is explained by properly including quantum statistical effects in the treatment of atomic collisions. From our data, we extract the difference between the triplet and singlet s-wave scattering lengths, at−as=60(10) pm, in agreement with existing theories. At densities above 1017 cm−3, weakly resolved structures appeared in the ESR spectra, interpreted in terms of electron spin waves. We consider exchange and dipolar interactions to possibly induce the spin waves.
We have confined over 5\ifmmode\times\else\texttimes\fi{}1012{10}^{12}1012 atoms of hydrogen in a static magnetic trap. The atoms are loaded into the trap by precooling with a dilution refrigerator. At operating densities near 1\ifmmode\times\else\texttimes\fi{}1013{10}^{13}1013 ${\mathrm{cm}}^{\mathrm{\ensuremath{-}}3}$ the gas is observed to be electron and nuclear polarized in the uppermost hyperfine state. The long lifetime of the trapped gas (over 20 min) suggests that it is thermally decoupled from the wall and has evaporatively cooled to a temperature of about 40 mK. The residual decay of the gas density is consistent with spin relaxation induced by dipolar interactions between atoms.
The identical spin rotation effect is the quantum mechanical collisional effect underlying the transverse nuclear spin waves recently seen in dilute non degenerate gases in Paris [3He] and at Cornell University [H↓]. This mechanism could in principle give rise, at low enough temperatures, to hydrodynamic oscillatory modes associated with any non diagonal elements of the atomic internal density matrix (generalized spin waves or coherences waves). Starting from a quantum Boltzmann equation recently derived for the study of 4-component atomic hydrogen, we show that the current of any transverse quantity (hyperfine or Zeeman coherence) does indeed precess around molecular exchange fields. Unhappily, in most cases, the oscillatory modes associated with these transverse quantities are heavily damped. The first intrinsic cause of damping of these waves is spin exchange. We study the conditions under which this damping is minimized in both zero field and in high magnetic field. Numerical values of all relevant parameters for the description of spin transport properties in atomic hydrogen are given in the appendices.
We present an experimental study of electron spin waves in atomic hydrogen gas compressed to high densities of ∼5 × 10 18 cm −3 at temperatures ranging from 0.26 to 0.6 K in the strong magnetic field of 4.6 T. Hydrogen gas is in a quantum regime when the thermal de-Broglie wavelength is much larger than the s -wave scattering length. In this regime the identical particle effects play a major role in atomic collisions and lead to the identical spin rotation effect (ISR). We observed a variety of spin wave modes caused by this effect with strong dependence on the magnetic potential caused by variations of the polarizing magnetic field. We demonstrate confinement of the ISR modes in the magnetic potential and manipulate their properties by changing the spatial profile of the magnetic field. We have found that at a high enough density of H gas the magnons accumulate in their ground state in the magnetic trap and exhibit long coherence, which has a profound effect on the electron spin resonance spectra. Such macroscopic accumulation of the ground state occurs at a certain critical density of hydrogen gas, where the chemical potential of the magnons becomes equal to the energy of their ground state in the trapping potential.