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

Observation of Bose-Einstein condensation of molecules

Claudiu Andrei Stan, Martin W. Zwierlein, Christian H. Schunck, S. M. F. Raupach, Wolfgang Ketterle

Published Jan 1, 2004• 22 citations
Publisher

Abstract

We have observed Bose-Einstein condensation of molecules, created from a spin mixture of fermionic 6Li atoms. The condensate realizes the limit of tightly bound fermion pairs in the crossover between BCS and BEC superfluidity.
DOI
10.1364/iqec.2004.imi4

Related papers

Observation of Bose-Einstein Condensation of Molecules

Martin W. Zwierlein, Claudiu A. Stan, Christian H. Schunck +4 more

We have observed Bose-Einstein condensation of molecules. When a spin mixture of fermionic 6Li atoms was evaporatively cooled in an optical dipole trap near a Feshbach resonance, the atomic gas was converted into 6Li2 molecules. Below 600 nK, a Bose-Einstein condensate of up to 900 000 molecules was identified by the sudden onset of a bimodal density distribution. This condensate realizes the limit of tightly bound fermion pairs in the crossover between BCS superfluidity and Bose-Einstein condensation.

arXiv:cond-mat/0311617•Physical Review Letters•Dec 15, 2003•938 citations

Molecular BEC and the crossover to a fermionic superfluid

M. Bartenstein, A. Altmeyer, S. Riedl +5 more

The paper gives an overview of the recent developments in the field of ultracold fermionic quantum gases. In particular, results obtained on an ultracold spin-mixture of /sup 6/Li atoms in a series of experiments performed in Innsbruck is presented . Bose-Einstein condensation of strongly bound atom pairs (molecules) , the reversible crossover to a degenerate Fermi gas, measurements of collective excitation modes, and spectroscopic observation of pairing in a strongly interacting Fermi gas of atoms are also discussed. The experimental results provide strong evidence for superfluidity.

European Quantum Electronics Conference (EQEC)•Jan 18, 2006•0 citations

FERMIONIC SUPERFLUIDITY AND THE BEC-BCS CROSSOVER IN ULTRACOLD ATOMIC FERMI GASES

Martin W. Zwierlein

In our recent experiments at MIT, superfluidity has been observed in a strongly interacting atomic Fermi gas. These systems constitute a novel form of matter with model character: One can vary the temperature, density and dimensionality, the number of “spin up” versus “spin down” fermions, and, most remarkably, the interactions can be precisely controlled over an enormous range. This allows to study the crossover of a Bose-Einstein condensate of tightly bound molecules to a Bardeen-Cooper-Schrieffer superfluid of long-range Cooper pairs. Superfluidity in this crossover regime is demonstrated by setting the gas under rotation and observing ordered lattices of quantized vortices [1]. Thanks to its strong interactions, the gas is a high-temperature superfluid: Scaled to the density of electrons in a metal, superfluidity would occur already far above room temperature. A new regime is entered when the number of spin up versus spin down atoms is imbalanced. In this case, not every spin up atom can find a spin down partner. The ground state of such a system has been under debate for over 40 years. We observe the breakdown of superfluidity at a critical imbalance, the Chandrasekhar-Clogston limit [2]. The superfluid gives way to an intriguing, strongly-interacting Fermi gas with unequal spin populations [3, 4].

Foundations of Quantum Mechanics in the Light of New Technology•Jun 1, 2009•0 citations

A molecular Bose-Einstein condensate emerges from a Fermi sea

Markus Greiner, Cindy A. Regal, Deborah Jin

The realization of fermionic superfluidity in a dilute gas of atoms, analogous to superconductivity in metals, is a long-standing goal of ultracold gas research. Beyond being a new example of this fascinating quantum phenomenon, fermionic superfluidity in an atomic gas holds the promise of adjustable interactions and the ability to tune continuously from BCS-type superfluidity to Bose-Einstein condensation (BEC). This crossover between BCS superfluidity of correlated atom pairs in momentum space and BEC of local pairs has long been of theoretical interest, motivated in part by the discovery of high Tc superconductors. In atomic Fermi gas experiments superfluidity has not yet been demonstrated; however recent experiments have made remarkable progress toward this goal. Starting from an ultracold Fermi gas experimenters have used Feshbach resonances to reversibly create molecules, i.e. composite bosons consisting of local fermion pairs. Furthermore, the experiments have shown that the resulting diatomic molecules can have surprisingly long lifetimes. Here we report the conversion of a Fermi sea of atoms into a molecular BEC. In addition to being the first molecular condensate in thermal equilibrium, this BEC represents one extreme of the predicted BCS-BEC continuum.

arXiv:cond-mat/0311172•Nov 7, 2003•4 citations

Fermionic Superfluidity with Imbalanced Spin Populations

Martin W. Zwierlein, André Schirotzek, Christian H. Schunck +2 more

We have observed fermionic superfluidity with population imbalance and the Clogston limit of superfluidity in an ultracold Fermi mixture [Zwierlein et al,2006]. Importantly, this demonstrated that in the case of population imbalance, there is no longer a smooth crossover from a Bose-Einstein condensate of molecules to a BCS type superfluid. Instead, as the pairing strength is varied, phase transitions occur between the superfluid and the normal state.

Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC)•Jun 1, 2007•0 citations

STUDY OF BARDEEN COOPER STATE (BCS) TO BOSE EINSTEIN CONDENSATION (BEC) CROSSOVER

AMITESH KUMAR, R.K. VERMA

This study presents a simple idea and a conceptual understandingof the crossover from the Bardeen Cooper (BCS) state of weakly-correlatedpairs of fermions to the Bose{Einstein condensation (BEC) of diatomicmolecules in the atomic Fermi gas. In the context of ultra cold Fermi gases,a BCS-BEC crossover means that by tuning the interaction strength, onegoes from a BCS state to a BEC state without encountering a phase transition.BEC state is a Bose-Einstein condensate of two-atom molecules (boundfermions), while the BCS state is made up of pair of atoms. The differencebetween the pairs and the molecules is that the molecules are localized inthe real space, whereas the BCS pairs are made of two particles with oppositemomenta in the momentum space.

THE SCIENTIFIC TEMPER•Jul 25, 2019•0 citations
We have observed Bose-Einstein condensation of molecules. When a spin mixture of fermionic 6Li atoms was evaporatively cooled in an optical dipole trap near a Feshbach resonance, the atomic gas was converted into 6Li2 molecules. Below 600 nK, a Bose-Einstein condensate of up to 900 000 molecules was identified by the sudden onset of a bimodal density distribution. This condensate realizes the limit of tightly bound fermion pairs in the crossover between BCS superfluidity and Bose-Einstein condensation.
The paper gives an overview of the recent developments in the field of ultracold fermionic quantum gases. In particular, results obtained on an ultracold spin-mixture of /sup 6/Li atoms in a series of experiments performed in Innsbruck is presented . Bose-Einstein condensation of strongly bound atom pairs (molecules) , the reversible crossover to a degenerate Fermi gas, measurements of collective excitation modes, and spectroscopic observation of pairing in a strongly interacting Fermi gas of atoms are also discussed. The experimental results provide strong evidence for superfluidity.
In our recent experiments at MIT, superfluidity has been observed in a strongly interacting atomic Fermi gas. These systems constitute a novel form of matter with model character: One can vary the temperature, density and dimensionality, the number of “spin up” versus “spin down” fermions, and, most remarkably, the interactions can be precisely controlled over an enormous range. This allows to study the crossover of a Bose-Einstein condensate of tightly bound molecules to a Bardeen-Cooper-Schrieffer superfluid of long-range Cooper pairs. Superfluidity in this crossover regime is demonstrated by setting the gas under rotation and observing ordered lattices of quantized vortices [1]. Thanks to its strong interactions, the gas is a high-temperature superfluid: Scaled to the density of electrons in a metal, superfluidity would occur already far above room temperature. A new regime is entered when the number of spin up versus spin down atoms is imbalanced. In this case, not every spin up atom can find a spin down partner. The ground state of such a system has been under debate for over 40 years. We observe the breakdown of superfluidity at a critical imbalance, the Chandrasekhar-Clogston limit [2]. The superfluid gives way to an intriguing, strongly-interacting Fermi gas with unequal spin populations [3, 4].
The realization of fermionic superfluidity in a dilute gas of atoms, analogous to superconductivity in metals, is a long-standing goal of ultracold gas research. Beyond being a new example of this fascinating quantum phenomenon, fermionic superfluidity in an atomic gas holds the promise of adjustable interactions and the ability to tune continuously from BCS-type superfluidity to Bose-Einstein condensation (BEC). This crossover between BCS superfluidity of correlated atom pairs in momentum space and BEC of local pairs has long been of theoretical interest, motivated in part by the discovery of high Tc superconductors. In atomic Fermi gas experiments superfluidity has not yet been demonstrated; however recent experiments have made remarkable progress toward this goal. Starting from an ultracold Fermi gas experimenters have used Feshbach resonances to reversibly create molecules, i.e. composite bosons consisting of local fermion pairs. Furthermore, the experiments have shown that the resulting diatomic molecules can have surprisingly long lifetimes. Here we report the conversion of a Fermi sea of atoms into a molecular BEC. In addition to being the first molecular condensate in thermal equilibrium, this BEC represents one extreme of the predicted BCS-BEC continuum.
This study presents a simple idea and a conceptual understandingof the crossover from the Bardeen Cooper (BCS) state of weakly-correlatedpairs of fermions to the Bose{Einstein condensation (BEC) of diatomicmolecules in the atomic Fermi gas. In the context of ultra cold Fermi gases,a BCS-BEC crossover means that by tuning the interaction strength, onegoes from a BCS state to a BEC state without encountering a phase transition.BEC state is a Bose-Einstein condensate of two-atom molecules (boundfermions), while the BCS state is made up of pair of atoms. The differencebetween the pairs and the molecules is that the molecules are localized inthe real space, whereas the BCS pairs are made of two particles with oppositemomenta in the momentum space.