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

Conference on Lasers and Electro-Optics Pacific Rim (CLEO-PR)

Single atom laser: recent experiments

Kyungwon An

Published Jan 20, 2003• 0 citations
Publisher

Abstract

The single-atom microlaser is one and the only type of single atom lasers realized experimentally so far. The gain medium is a beam of excited, non-interacting two-level atoms (/spl lambda/=791 nm, /sup 3/P/sup 1//spl rarr//sup 1/S/sub 0/ transition of /sup 138/Ba) entering an ultra-low loss resonator one at a time. This laser device utilizes the coherent atom-cavity interaction, often referred to as quantized Rabi oscillation, as the light amplification method, With the mean atom number about unity, tens of photons could be stored inside the cavity. The laser oscillation persisted with the mean number of atoms in the cavity well below unity.

DOI
10.1109/cleopr.1999.817740

Related papers

Microlaser: a fundamental quantum generator of light

Kyungwon An, Ramachandra Rao Dasari, Michael S. Feld

We have achieved the first realization of a single atom microlaser, a laser oscillator with only one atom in an optical resonator. In the experiment a beam of two-level barium atoms traverses an ultrahigh Q single-mode cavity. The atoms are inverted by a (pi) -pulse field before they enter the cavity. Laser oscillation ((lambda) equals 791 nm) has been observed, with the mean number of atoms inside the mode <N> as small as 0.1, resulting in the mean number of photons in the mode <N> or 0.14. To understand the results quantitatively we used a fully-quantized one-atom microlaser theory adapted from its counterpart micromaser theory. The present theory was found to be in good agreement with the data for small <N> and <n>. Discrepancy between experiment and theory was observed for <n> very much greater than 1 and <N> approximately equal to 1. This discrepancy may be explained by the standing-wave nature of the cavity mode, in combination with the saturation effect occurring at large cavity photon number, as well as by the breakdown of single-atom interaction assumption in the theory for <N> greater than or equal to 1.

Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE•May 6, 1996•2 citations

Microlaser: A laser with One Atom in an Optical Resonator

Kyungwon An, James Childs, Ramachandra Rao Dasari +1 more

We have demonstrated laser oscillation with one atom in an optical resonator. In our experiment a beam of $^{138}\mathrm{Ba}$ atoms traverses a single-mode cavity with a finesse of 8 \ifmmode\times\else\texttimes\fi{} ${10}^{5}$. The atoms are excited by a $\ensuremath{\pi}$ pulse from the $^{1}S_{0}$ ground state to the $^{3}P_{1}(m=0)$ excited state before they enter the cavity. Laser oscillation at 791 nm ($^{3}P_{1}\ensuremath{\rightarrow}^{1}S_{0}$) has been observed, with the mean number of atoms inside the mode ranging from 0.1 to 1.0, resulting in the mean number of photons inside the cavity changing from 0.14 to 11. The results are in good agreement with a fully quantized micromaser theory adapted to our experiment.

Physical Review Letters•Dec 19, 1994•283 citations

The single atom laser: a quantized Rabi oscillator

Kyungwon An, Changhuei Yang, Ramachandra Rao Dasari +1 more

Summary form only given. We have recently developed the first working single-atom microlaser in which coherent light is generated by means of the interaction of a single two-level atom with a single mode of the radiation field. The photon generation process follows the Jaynes-Cummings model, and photon buildup is initiated by vacuum Rabi oscillations, not by spontaneous emission as in conventional lasers. We measured the mean photon number in the cavity (n) as a function of the average number of atoms present there . Laser oscillation was observed with as small as 0.1, resulting in (n) of 0.1.

•Jun 7, 1996•0 citations

Semiclassical four-level single-atom laser

Kyungwon An, Michael S. Feld

The recent single-atom microlaser experiment [K. An et al., Phys. Rev. Lett. 73, 3375 (1994)], in which a stream of inverted two-level atoms is injected into an ultrahigh $Q$ cavity, can be understood in the context of a semiclassical four-level laser model. Transit time broadening due to short atom-cavity interaction time effectively introduces nonradiative decay of the two levels in the model. The steady-state solution of semiclassical photon and atom rate equations for the intracavity mean photon number versus the intracavity atom number provides a good fit to the experimental data.

Physical Review A•Aug 1, 1997•24 citations

Experiments with the One-atom-maser

Linas Urbonas

There are only fistful of systems in physics that can be described by an exact theory from first principles and, at the same time, can be investigated under experimental conditions approaching the idealized theoretical ones. The one-atom-maser or micromaser provides such an example, making a detailed study of the fundamental properties of the atom-field interaction possible. The situation realized in a micromaser is very close to the ideal case of a single two-level atom interacting with a single quantized mode of a cavity field. In the micromaser the atoms have a dual purpose of both pumping the field and also probing it via measurements of the outgoing atoms. Any other means of measuring the field inside the resonator has the detrimental effect of lowering its Q-factor and thereby the photon storage time. The long photon storage time of the resonator allows for the decay of the field to be negligible during the passage of an atom and its interaction with the field. The behavior of atoms in a cavity is governed by the oscillatory exchange of energy between the atoms and the field, which is called Rabi oscillation. For cavity fields in the vacuum and few photon number states (Fock states), Rabi oscillations have been measured in the past. To prevent thermal effects from polluting the pure number states these experiments were performed at low temperatures (below 1 K). However, the observed resolution of the Rabi oscillations measurements was quite disappointing (only about 2% of the predicted theoretical value) and precluded more ambitious experiments like atom-atom correlations or time resolved investigations of the maser field dynamics. The observed contrast of Rabi oscillations can be considered as a figure of merit for the experimental resolution of quantum features of a maser field. Therefore, a high resolution in the measurements of Rabi oscillations is crucial. This thesis describes the methods and improvements applied to enhance the resolution of Rabi oscillations by a factor of 8. The following upgrades and developments proved to be crucial in this work: 1) The base temperature of the cryogenic system was lowered to 0.3 K, i.e. one third of the original value. At the same time, the time during which the system remains at the base temperature was improved by almost of an order of magnitude (to more than 12 h). 2) For the promotion of the atoms to the Rydberg regime new three-step diode laser setup was constructed. The excitation efficiency compared to the old dye laser was increased by two orders. Using top-of-fringe stabilization with new spectroscopic methods, specially designed error detection and feedback schemes as well as state-of-the-art PID regulators the continuous locking of lasers is about 8 h (compared to about 20 min with the old dye laser system). 3) The flexibility of using the three step excitation allows to excite different maser states and for the first time to investigate pure maser transition. 4) Various improvements on the atomic oven and the channeltron detection unit led to the reliable and stable production and detection of the atomic beam. Observed distribution of the atomic beam statistics reaches to within 6% the Poisson limit which is expected in the absence of experimental imperfections. 5) New developed techniques in magnetic field compensation allow to perform such measurements with two orders of magnitude better accuracy compared to the previous experiments. To demonstrate the new capabilities of the apparatus and to apply its improved resolution of quantum fields we performed a previously impossible in-depth analysis of mean photon number and the atomic inversion produced by a micromaser for various detunings between the cavity- and atomic resonance frequency.

•Jan 1, 2009•0 citations

Theory of the micromaser

Marlan O. Scully, Muhammad Suhail Zubairy

The development of a single-atom maser or a micromaser allows a detailed study of the atom–field interaction. The situation realized is very close to the ideal case of a single two-level atom interacting with a single-mode quantized field as treated in Section 6.2. In a micromaser a stream of two-level atoms is injected into a superconducting cavity with a high quality factor. The injection rate can be such that only one atom is present inside the resonator at any time. Due to the high quality factor of the cavity, the radiation decay time is much larger than the characteristic time of the atom–field interaction, which is given by the inverse of the single-photon Rabi frequency. Therefore, a field is built up inside the cavity when the mean time between the atoms injected into the cavity is shorter than the cavity decay time. A micromaser, therefore, allows sustained oscillations with less than one atom on the average in the cavity. The realization of a single-atom maser or a micromaser has been made possible due to the enormous progress in the construction of superconducting cavities together with the laser preparation of highly excited atoms called Rydberg atoms. The quality factor of the superconducting cavities is high enough for periodic energy exchanges between atom and cavity field to be observed. The interesting properties of the Rydberg atoms make them ideal for micromasers. In Rydberg atoms the probability of induced transitions between adjacent states becomes very large and scales as n 4 , where n denotes the principle quantum number.

Cambridge University Press eBooks•Sep 4, 1997•1 citation
The single-atom microlaser is one and the only type of single atom lasers realized experimentally so far. The gain medium is a beam of excited, non-interacting two-level atoms (/spl lambda/=791 nm, /sup 3/P/sup 1//spl rarr//sup 1/S/sub 0/ transition of /sup 138/Ba) entering an ultra-low loss resonator one at a time. This laser device utilizes the coherent atom-cavity interaction, often referred to as quantized Rabi oscillation, as the light amplification method, With the mean atom number about unity, tens of photons could be stored inside the cavity. The laser oscillation persisted with the mean number of atoms in the cavity well below unity.
We have achieved the first realization of a single atom microlaser, a laser oscillator with only one atom in an optical resonator. In the experiment a beam of two-level barium atoms traverses an ultrahigh Q single-mode cavity. The atoms are inverted by a (pi) -pulse field before they enter the cavity. Laser oscillation ((lambda) equals 791 nm) has been observed, with the mean number of atoms inside the mode <N> as small as 0.1, resulting in the mean number of photons in the mode <N> or 0.14. To understand the results quantitatively we used a fully-quantized one-atom microlaser theory adapted from its counterpart micromaser theory. The present theory was found to be in good agreement with the data for small <N> and <n>. Discrepancy between experiment and theory was observed for <n> very much greater than 1 and <N> approximately equal to 1. This discrepancy may be explained by the standing-wave nature of the cavity mode, in combination with the saturation effect occurring at large cavity photon number, as well as by the breakdown of single-atom interaction assumption in the theory for <N> greater than or equal to 1.
We have demonstrated laser oscillation with one atom in an optical resonator. In our experiment a beam of 138Ba^{138}\mathrm{Ba}138Ba atoms traverses a single-mode cavity with a finesse of 8 \ifmmode\times\else\texttimes\fi{} 105{10}^{5}105. The atoms are excited by a $\ensuremath{\pi}$ pulse from the 1S0^{1}S_{0}1S0​ ground state to the 3P1(m=0)^{3}P_{1}(m=0)3P1​(m=0) excited state before they enter the cavity. Laser oscillation at 791 nm ($^{3}P_{1}\ensuremath{\rightarrow}^{1}S_{0}$) has been observed, with the mean number of atoms inside the mode ranging from 0.1 to 1.0, resulting in the mean number of photons inside the cavity changing from 0.14 to 11. The results are in good agreement with a fully quantized micromaser theory adapted to our experiment.
Summary form only given. We have recently developed the first working single-atom microlaser in which coherent light is generated by means of the interaction of a single two-level atom with a single mode of the radiation field. The photon generation process follows the Jaynes-Cummings model, and photon buildup is initiated by vacuum Rabi oscillations, not by spontaneous emission as in conventional lasers. We measured the mean photon number in the cavity (n) as a function of the average number of atoms present there . Laser oscillation was observed with as small as 0.1, resulting in (n) of 0.1.
The recent single-atom microlaser experiment [K. An et al., Phys. Rev. Lett. 73, 3375 (1994)], in which a stream of inverted two-level atoms is injected into an ultrahigh QQQ cavity, can be understood in the context of a semiclassical four-level laser model. Transit time broadening due to short atom-cavity interaction time effectively introduces nonradiative decay of the two levels in the model. The steady-state solution of semiclassical photon and atom rate equations for the intracavity mean photon number versus the intracavity atom number provides a good fit to the experimental data.
There are only fistful of systems in physics that can be described by an exact theory from first principles and, at the same time, can be investigated under experimental conditions approaching the idealized theoretical ones. The one-atom-maser or micromaser provides such an example, making a detailed study of the fundamental properties of the atom-field interaction possible. The situation realized in a micromaser is very close to the ideal case of a single two-level atom interacting with a single quantized mode of a cavity field. In the micromaser the atoms have a dual purpose of both pumping the field and also probing it via measurements of the outgoing atoms. Any other means of measuring the field inside the resonator has the detrimental effect of lowering its Q-factor and thereby the photon storage time. The long photon storage time of the resonator allows for the decay of the field to be negligible during the passage of an atom and its interaction with the field. The behavior of atoms in a cavity is governed by the oscillatory exchange of energy between the atoms and the field, which is called Rabi oscillation. For cavity fields in the vacuum and few photon number states (Fock states), Rabi oscillations have been measured in the past. To prevent thermal effects from polluting the pure number states these experiments were performed at low temperatures (below 1 K). However, the observed resolution of the Rabi oscillations measurements was quite disappointing (only about 2% of the predicted theoretical value) and precluded more ambitious experiments like atom-atom correlations or time resolved investigations of the maser field dynamics. The observed contrast of Rabi oscillations can be considered as a figure of merit for the experimental resolution of quantum features of a maser field. Therefore, a high resolution in the measurements of Rabi oscillations is crucial. This thesis describes the methods and improvements applied to enhance the resolution of Rabi oscillations by a factor of 8. The following upgrades and developments proved to be crucial in this work: 1) The base temperature of the cryogenic system was lowered to 0.3 K, i.e. one third of the original value. At the same time, the time during which the system remains at the base temperature was improved by almost of an order of magnitude (to more than 12 h). 2) For the promotion of the atoms to the Rydberg regime new three-step diode laser setup was constructed. The excitation efficiency compared to the old dye laser was increased by two orders. Using top-of-fringe stabilization with new spectroscopic methods, specially designed error detection and feedback schemes as well as state-of-the-art PID regulators the continuous locking of lasers is about 8 h (compared to about 20 min with the old dye laser system). 3) The flexibility of using the three step excitation allows to excite different maser states and for the first time to investigate pure maser transition. 4) Various improvements on the atomic oven and the channeltron detection unit led to the reliable and stable production and detection of the atomic beam. Observed distribution of the atomic beam statistics reaches to within 6% the Poisson limit which is expected in the absence of experimental imperfections. 5) New developed techniques in magnetic field compensation allow to perform such measurements with two orders of magnitude better accuracy compared to the previous experiments. To demonstrate the new capabilities of the apparatus and to apply its improved resolution of quantum fields we performed a previously impossible in-depth analysis of mean photon number and the atomic inversion produced by a micromaser for various detunings between the cavity- and atomic resonance frequency.
The development of a single-atom maser or a micromaser allows a detailed study of the atom–field interaction. The situation realized is very close to the ideal case of a single two-level atom interacting with a single-mode quantized field as treated in Section 6.2. In a micromaser a stream of two-level atoms is injected into a superconducting cavity with a high quality factor. The injection rate can be such that only one atom is present inside the resonator at any time. Due to the high quality factor of the cavity, the radiation decay time is much larger than the characteristic time of the atom–field interaction, which is given by the inverse of the single-photon Rabi frequency. Therefore, a field is built up inside the cavity when the mean time between the atoms injected into the cavity is shorter than the cavity decay time. A micromaser, therefore, allows sustained oscillations with less than one atom on the average in the cavity. The realization of a single-atom maser or a micromaser has been made possible due to the enormous progress in the construction of superconducting cavities together with the laser preparation of highly excited atoms called Rydberg atoms. The quality factor of the superconducting cavities is high enough for periodic energy exchanges between atom and cavity field to be observed. The interesting properties of the Rydberg atoms make them ideal for micromasers. In Rydberg atoms the probability of induced transitions between adjacent states becomes very large and scales as n 4 , where n denotes the principle quantum number.