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

Quantum and Semiclassical Optics Journal of the European Optical Society Part B

An atom laser based on evaporative cooling

Howard M. Wiseman, Ana María Guerra Martins, Daniel F. Walls

Published Jun 1, 1996• 60 citations
Publisher

Abstract

An atom laser is a device which would ideally produce a coherent excitation of a single mode of the Bose-atom field. That is to say, an atom laser field would have a well defined number of atoms, and a slow rate of phase diffusion. Here we consider an atom laser model recently proposed by Holland et al, based on evaporative cooling of atoms. We extend their model, and give approximate analytical results for the time-dependent intensity and phase statistics of the atom laser in different regimes. Although the intensity fluctuations may be relatively small, the laser linewidth is always in excess of the bare linewidth of the laser mode. Nevertheless, in one regime (weak collisions), the laser linewidth may be less than the output flux of atoms, which is a minimum requirement for considering the output to be coherent.

DOI
10.1088/1355-5111/8/3/032

Related papers

An atom laser based on dark-state cooling: a detailed description

Howard M. Wiseman, Keith R. Burnett, Matthew J. Collett

It was proposed by two of us (Wiseman H M and Collett M J 1995 Phys. Lett. A 202 246) that a device producing a coherent atomic wave (that is, an atom laser) could be built using dark-state cooling of atoms in a trap. Here we present a more complete analysis of this system, including the effects of atomic interactions through dipole-dipole coupling and hard-core collisions. We show that for reasonable physical parameters the dipole interactions have little contribution to the atomic dynamics. In contrast, the hard-core collisions are likely to dominate the laser linewidth. In fact, it would appear necessary to select (or produce) a species with a hard-core scattering radius of much less than one nm in order for the output of the device to be phase coherent.

Journal of Physics B Atomic Molecular and Optical Physics•Aug 3, 1999•4 citations

Steady-state quantum statistics of a non-Markovian atom laser. II

Ashton S. Bradley, J. J. Hope, Matthew J. Collett

We present a steady-state analysis of a quantum-mechanical model of an atom laser. A single-mode atomic trap coupled to a continuum of external modes is driven by a saturable pumping mechanism. In the dilute flux regime, where atom-atom interactions are negligible in the output, we find an analytic form for the linewidth and frequency shift of the laser. This result does not make the Born-Markov approximation, but is based on the far less restrictive ``self-consistent Markov approximation.'' The more exact treatment has a different effective damping rate and occupation of the lasing mode, as well as a shifted frequency and linewidth of the output. We examine gravitational damping numerically, finding linewidths and frequency shifts for a range of pumping rates. We treat mean-field damping analytically, finding a memory function for the Thomas-Fermi regime. The occupation and linewidth are found to have a nonlinear scaling behavior which has implications for the stability of atom lasers.

arXiv:cond-mat/0210688•Physical Review A•Dec 22, 2003•7 citations

Defining the (atom) laser

Howard M. Wiseman

An atom laser is an as-yet unrealized device that would produce an atomic field analogous to the electromagnetic field of a photon laser. Here I argue that for this analogy to be meaningful it is necessary to have a precise definition of a laser that applies equally to photon or atom (or any other boson) lasers. The definition I propose uses the fundamental principle that the output of a laser is well approximated by a classical wave of fixed intensity and phase. This principle yields four quantitative conditions that the output of a device must satisfy in order for the device to be considered a laser. While explaining these requirements, I analyze the similarities and differences between atom and photon lasers. I next show how these conditions are satisfied first by an idealized photon laser model, and then by a more general model that can apply to atom lasers also. Lastly, I briefly discuss the current proposals for atom lasers and whether they could be true lasers.

Physical Review A•Sep 1, 1997•96 citations

What is an atom laser?

Howard M. Wiseman

An atom laser is a hypothetical device which would produce an atomic field analogous to the electromagnetic field of a photon laser. Here I argue that for this analogy to be meaningful it is necessary to have a precise definition of a laser which applies equally to photon or atom lasers. The definition I propose is based upon the principle that the output of a laser is well-approximated by a classical wave of fixed intensity and phase. This principle yields four quantitative conditions which the output of a device must satisfy in order for that device to be considered a laser. While explaining these requirements, I analyse the similarities and differences between atom and photon lasers. I show how these conditions are satisfied first by an idealized photon laser model, and then by a more generic model which can apply to atom lasers also. Lastly, I briefly discuss the current proposals for atom lasers and whether they could be true lasers.

arXiv:quant-ph/9611033•Quantum Electronics and Laser Science Conference•Nov 20, 1996•0 citations

The coherence and spectra of a Bose condensate generated by an atomic laser

A. V. Kozlovskiĭ

The first-order coherence dynamics of a Bose condensate generated by a cw atomic laser with evaporative cooling is analyzed. For the atomic-laser multimode model, the coherence functions and atomic field spectra are calculated by the master equation technique. Elastic collisions in the trapped atomic gas lead to significant broadening of the atomic laser line, a shift of its center, and a multi peak structure of the spectra. The oscillatory time dynamics of the atomic-field coherence function is studied. For the atomic laser, the free phase diffusion of the field typical of optical lasers, and characterized by monotonically decreasing mean field with a constant mean phase, is absent due to elastic collisions.

Optics and Spectroscopy•Jul 1, 2003•0 citations

Atom laser coherence and its control using feedback

L. K. Thomsen, Howard M. Wiseman

We present a quantum-mechanical treatment of the coherence properties of a single-mode atom laser. Specifically, we focus on the quantum phase noise of the atomic field as expressed by the first-order coherence function, for which we derive analytical expressions in various regimes. The decay of this function is characterized by the coherence time, or its reciprocal, the linewidth. A crucial contributor to the linewidth is the collisional interaction of the atoms. We find four distinct regimes for the linewidth with increasing interaction strength. These range from the standard laser linewidth, through quadratic and linear regimes, to another constant regime due to quantum revivals of the coherence function. The laser output is only coherent (Bose degenerate) up to the linear regime. However, we show that application of a quantum nondemolition measurement and feedback scheme will increase, by many orders of magnitude, the range of interaction strengths for which it remains coherent.

•Jan 1, 2001•0 citations
An atom laser is a device which would ideally produce a coherent excitation of a single mode of the Bose-atom field. That is to say, an atom laser field would have a well defined number of atoms, and a slow rate of phase diffusion. Here we consider an atom laser model recently proposed by Holland et al, based on evaporative cooling of atoms. We extend their model, and give approximate analytical results for the time-dependent intensity and phase statistics of the atom laser in different regimes. Although the intensity fluctuations may be relatively small, the laser linewidth is always in excess of the bare linewidth of the laser mode. Nevertheless, in one regime (weak collisions), the laser linewidth may be less than the output flux of atoms, which is a minimum requirement for considering the output to be coherent.
It was proposed by two of us (Wiseman H M and Collett M J 1995 Phys. Lett. A 202 246) that a device producing a coherent atomic wave (that is, an atom laser) could be built using dark-state cooling of atoms in a trap. Here we present a more complete analysis of this system, including the effects of atomic interactions through dipole-dipole coupling and hard-core collisions. We show that for reasonable physical parameters the dipole interactions have little contribution to the atomic dynamics. In contrast, the hard-core collisions are likely to dominate the laser linewidth. In fact, it would appear necessary to select (or produce) a species with a hard-core scattering radius of much less than one nm in order for the output of the device to be phase coherent.
We present a steady-state analysis of a quantum-mechanical model of an atom laser. A single-mode atomic trap coupled to a continuum of external modes is driven by a saturable pumping mechanism. In the dilute flux regime, where atom-atom interactions are negligible in the output, we find an analytic form for the linewidth and frequency shift of the laser. This result does not make the Born-Markov approximation, but is based on the far less restrictive ``self-consistent Markov approximation.'' The more exact treatment has a different effective damping rate and occupation of the lasing mode, as well as a shifted frequency and linewidth of the output. We examine gravitational damping numerically, finding linewidths and frequency shifts for a range of pumping rates. We treat mean-field damping analytically, finding a memory function for the Thomas-Fermi regime. The occupation and linewidth are found to have a nonlinear scaling behavior which has implications for the stability of atom lasers.
An atom laser is an as-yet unrealized device that would produce an atomic field analogous to the electromagnetic field of a photon laser. Here I argue that for this analogy to be meaningful it is necessary to have a precise definition of a laser that applies equally to photon or atom (or any other boson) lasers. The definition I propose uses the fundamental principle that the output of a laser is well approximated by a classical wave of fixed intensity and phase. This principle yields four quantitative conditions that the output of a device must satisfy in order for the device to be considered a laser. While explaining these requirements, I analyze the similarities and differences between atom and photon lasers. I next show how these conditions are satisfied first by an idealized photon laser model, and then by a more general model that can apply to atom lasers also. Lastly, I briefly discuss the current proposals for atom lasers and whether they could be true lasers.
An atom laser is a hypothetical device which would produce an atomic field analogous to the electromagnetic field of a photon laser. Here I argue that for this analogy to be meaningful it is necessary to have a precise definition of a laser which applies equally to photon or atom lasers. The definition I propose is based upon the principle that the output of a laser is well-approximated by a classical wave of fixed intensity and phase. This principle yields four quantitative conditions which the output of a device must satisfy in order for that device to be considered a laser. While explaining these requirements, I analyse the similarities and differences between atom and photon lasers. I show how these conditions are satisfied first by an idealized photon laser model, and then by a more generic model which can apply to atom lasers also. Lastly, I briefly discuss the current proposals for atom lasers and whether they could be true lasers.
The first-order coherence dynamics of a Bose condensate generated by a cw atomic laser with evaporative cooling is analyzed. For the atomic-laser multimode model, the coherence functions and atomic field spectra are calculated by the master equation technique. Elastic collisions in the trapped atomic gas lead to significant broadening of the atomic laser line, a shift of its center, and a multi peak structure of the spectra. The oscillatory time dynamics of the atomic-field coherence function is studied. For the atomic laser, the free phase diffusion of the field typical of optical lasers, and characterized by monotonically decreasing mean field with a constant mean phase, is absent due to elastic collisions.
We present a quantum-mechanical treatment of the coherence properties of a single-mode atom laser. Specifically, we focus on the quantum phase noise of the atomic field as expressed by the first-order coherence function, for which we derive analytical expressions in various regimes. The decay of this function is characterized by the coherence time, or its reciprocal, the linewidth. A crucial contributor to the linewidth is the collisional interaction of the atoms. We find four distinct regimes for the linewidth with increasing interaction strength. These range from the standard laser linewidth, through quadratic and linear regimes, to another constant regime due to quantum revivals of the coherence function. The laser output is only coherent (Bose degenerate) up to the linear regime. However, we show that application of a quantum nondemolition measurement and feedback scheme will increase, by many orders of magnitude, the range of interaction strengths for which it remains coherent.