2009
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Zwierlein, M W Fermionic superfluidity and the BEC-BCS crossover in ultracold atomic Fermi gases Proceedings Article In: Proceedings of the 9th International Symposium on Foundations of Quantum Mechanics in the Light of New Technology, ISQM-Tokyo 2008, 2009, ISBN: 981428212X | 9789814282123. @inproceedings{Zwierlein2009b,
title = {Fermionic superfluidity and the BEC-BCS crossover in ultracold atomic Fermi gases},
author = {M W Zwierlein},
isbn = {981428212X | 9789814282123},
year = {2009},
date = {2009-01-01},
booktitle = {Proceedings of the 9th International Symposium on Foundations of Quantum Mechanics in the Light of New Technology, ISQM-Tokyo 2008},
keywords = {},
pubstate = {published},
tppubtype = {inproceedings}
}
|
Schirotzek, A; Wu, C -H; Sommer, A; Zwierlein, M W Observation of Fermi polarons in a tunable Fermi liquid of ultracold atoms Journal Article In: Physical Review Letters, vol. 102, no. 23, 2009, ISSN: 00319007 10797114. @article{Schirotzek2009,
title = {Observation of Fermi polarons in a tunable Fermi liquid of ultracold atoms},
author = {A Schirotzek and C -H Wu and A Sommer and M W Zwierlein},
doi = {10.1103/PhysRevLett.102.230402},
issn = {00319007 10797114},
year = {2009},
date = {2009-01-01},
journal = {Physical Review Letters},
volume = {102},
number = {23},
abstract = {We have observed Fermi polarons, dressed spin-down impurities in a spin-up Fermi sea of ultracold atoms. The polaron manifests itself as a narrow peak in the impurities' rf spectrum that emerges from a broad incoherent background. We determine the polaron energy and the quasiparticle residue for various interaction strengths around a Feshbach resonance. At a critical interaction, we observe the transition from polaronic to molecular binding. Here, the imbalanced Fermi liquid undergoes a phase transition into a Bose liquid, coexisting with a Fermi sea. ? 2009 The American Physical Society.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
We have observed Fermi polarons, dressed spin-down impurities in a spin-up Fermi sea of ultracold atoms. The polaron manifests itself as a narrow peak in the impurities' rf spectrum that emerges from a broad incoherent background. We determine the polaron energy and the quasiparticle residue for various interaction strengths around a Feshbach resonance. At a critical interaction, we observe the transition from polaronic to molecular binding. Here, the imbalanced Fermi liquid undergoes a phase transition into a Bose liquid, coexisting with a Fermi sea. ? 2009 The American Physical Society. |
2008
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Zwierlein, M W Fermionic Superfluidity and the BEC-BCS Crossover in Ultracold Atomic Fermi Gases Proceedings Article In: Ishioka, Sachio; Fujikawa, Kazuo (Ed.): Proceedings of the 9th International Symposium on Foundations of Quantum Mechanics in the Light of New Technology - ISQM Tokyo 2008, World Scientific, Tokyo, Japan, 2008. @inproceedings{Zwierlein2008,
title = {Fermionic Superfluidity and the BEC-BCS Crossover in Ultracold Atomic Fermi Gases},
author = {M W Zwierlein},
editor = {Sachio Ishioka and Kazuo Fujikawa},
year = {2008},
date = {2008-01-01},
booktitle = {Proceedings of the 9th International Symposium on Foundations of Quantum Mechanics in the Light of New Technology - ISQM Tokyo 2008},
publisher = {World Scientific},
address = {Tokyo, Japan},
keywords = {},
pubstate = {published},
tppubtype = {inproceedings}
}
|
Ketterle, W; Zwierlein, M W Making, probing and understanding ultracold Fermi gases Proceedings Article In: Proceedings of the International School of Physics "Enrico Fermi", 2008, ISSN: 0074784X 18798195. @inproceedings{Ketterle2007,
title = {Making, probing and understanding ultracold Fermi gases},
author = {W Ketterle and M W Zwierlein},
doi = {10.3254/978-1-58603-846-5-95},
issn = {0074784X 18798195},
year = {2008},
date = {2008-01-01},
booktitle = {Proceedings of the International School of Physics "Enrico Fermi"},
volume = {164},
keywords = {},
pubstate = {published},
tppubtype = {inproceedings}
}
|
2007
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Baym, G; Pethick, C J; Yu, Z; Zwierlein, M W Coherence and clock shifts in ultracold fermi gases with resonant interactions Journal Article In: Physical Review Letters, vol. 99, no. 19, 2007, ISSN: 00319007 10797114. @article{Baym2007,
title = {Coherence and clock shifts in ultracold fermi gases with resonant interactions},
author = {G Baym and C J Pethick and Z Yu and M W Zwierlein},
doi = {10.1103/PhysRevLett.99.190407},
issn = {00319007 10797114},
year = {2007},
date = {2007-01-01},
journal = {Physical Review Letters},
volume = {99},
number = {19},
abstract = {Using arguments based on sum rules, we derive a general result for the average shifts of rf lines in Fermi gases in terms of interatomic interaction strengths and two-particle correlation functions. We show that near an interaction resonance shifts vary inversely with the atomic scattering length, rather than linearly as in dilute gases, thus accounting for the experimental observation that clock shifts remain finite at Feshbach resonances. ? 2007 The American Physical Society.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Using arguments based on sum rules, we derive a general result for the average shifts of rf lines in Fermi gases in terms of interatomic interaction strengths and two-particle correlation functions. We show that near an interaction resonance shifts vary inversely with the atomic scattering length, rather than linearly as in dilute gases, thus accounting for the experimental observation that clock shifts remain finite at Feshbach resonances. ? 2007 The American Physical Society. |
Schunck, C H; Shin, Y; Schirotzek, A; Zwierlein, M W; Ketterle, W Pairing without superfluidity: The ground state of an imbalanced fermi mixture Journal Article In: Science, vol. 316, no. 5826, 2007, ISSN: 00368075 10959203. @article{Schunck2007a,
title = {Pairing without superfluidity: The ground state of an imbalanced fermi mixture},
author = {C H Schunck and Y Shin and A Schirotzek and M W Zwierlein and W Ketterle},
doi = {10.1126/science.1140749},
issn = {00368075 10959203},
year = {2007},
date = {2007-01-01},
journal = {Science},
volume = {316},
number = {5826},
abstract = {We used radio-frequency spectroscopy to study pairing in the normal and superfluid phases of a strongly interacting Fermi gas with imbalanced spin populations. At high spin imbalances, the system does not become superfluid even at zero temperature. In this normal phase, full pairing of the minority atoms was observed. Hence, mismatched Fermi surfaces do not prevent pairing but can quench the superfluid state, thus realizing a system of fermion pairs that do not condense even at the lowest temperature.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
We used radio-frequency spectroscopy to study pairing in the normal and superfluid phases of a strongly interacting Fermi gas with imbalanced spin populations. At high spin imbalances, the system does not become superfluid even at zero temperature. In this normal phase, full pairing of the minority atoms was observed. Hence, mismatched Fermi surfaces do not prevent pairing but can quench the superfluid state, thus realizing a system of fermion pairs that do not condense even at the lowest temperature. |
Schunck, C H; Zwierlein, M W; Schirotzek, A; Ketterle, W Superfluid Expansion of a Rotating Fermi Gas Journal Article In: Physical Review Letters, vol. 98, no. 5, pp. 50404, 2007. @article{Schunck2007,
title = {Superfluid Expansion of a Rotating Fermi Gas},
author = {C H Schunck and M W Zwierlein and A Schirotzek and W Ketterle},
year = {2007},
date = {2007-01-01},
journal = {Physical Review Letters},
volume = {98},
number = {5},
pages = {50404},
publisher = {APS},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
|
2006
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Zwierlein, Martin W; Schunck, Christian H; Schirotzek, André; Ketterle, Wolfgang Direct Observation of the Superfluid Phase Transition in Ultracold Fermi Gases Journal Article In: Nature, vol. 442, pp. 54–58, 2006. @article{Zwierlein2006a,
title = {Direct Observation of the Superfluid Phase Transition in Ultracold Fermi Gases},
author = {Martin W Zwierlein and Christian H Schunck and André Schirotzek and Wolfgang Ketterle},
year = {2006},
date = {2006-01-01},
journal = {Nature},
volume = {442},
pages = {54--58},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
|
Zwierlein, Martin W; Schirotzek, André; Schunck, Christian H; Ketterle, Wolfgang Fermionic superfluidity with imbalanced spin populations Journal Article In: Science, vol. 311, no. 5760, pp. 492–496, 2006, ISSN: 00368075. @article{Zwierlein2006c,
title = {Fermionic superfluidity with imbalanced spin populations},
author = {Martin W Zwierlein and André Schirotzek and Christian H Schunck and Wolfgang Ketterle},
url = {http://www.sciencemag.org/cgi/doi/10.1126/science.1122318},
doi = {10.1126/science.1122318},
issn = {00368075},
year = {2006},
date = {2006-01-01},
journal = {Science},
volume = {311},
number = {5760},
pages = {492--496},
abstract = {We established superfluidity in a two-state mixture of ultracold fermionic atoms with imbalanced state populations. This study relates to the long-standing debate about the nature of the superfluid state in Fermi systems. Indicators for superfluidity were condensates of fermion pairs and vortices in rotating clouds. For strong interactions, near a Feshbach resonance, superfluidity was observed for a broad range of population imbalances. We mapped out the superfluid regime as a function of interaction strength and population imbalance and characterized the quantum phase transition to the normal state, known as the Pauli limit of superfluidity.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
We established superfluidity in a two-state mixture of ultracold fermionic atoms with imbalanced state populations. This study relates to the long-standing debate about the nature of the superfluid state in Fermi systems. Indicators for superfluidity were condensates of fermion pairs and vortices in rotating clouds. For strong interactions, near a Feshbach resonance, superfluidity was observed for a broad range of population imbalances. We mapped out the superfluid regime as a function of interaction strength and population imbalance and characterized the quantum phase transition to the normal state, known as the Pauli limit of superfluidity. |
Zwierlein, M W High-temperature superfluidity in an Ultracold Fermi Gas PhD Thesis 2006. @phdthesis{Zwierlein2006c,
title = {High-temperature superfluidity in an Ultracold Fermi Gas},
author = {M W Zwierlein},
year = {2006},
date = {2006-01-01},
booktitle = {Department of Physics},
volume = {PhD},
publisher = {Massachusetts Institute of Technology},
address = {Cambridge},
keywords = {},
pubstate = {published},
tppubtype = {phdthesis}
}
|
Shin, Y; Zwierlein, M W; Schunck, C H; Schirotzek, A; Ketterle, W Observation of Phase Separation in a Strongly Interacting Imbalanced Fermi Gas Journal Article In: Physical Review Letters, vol. 97, pp. 30401, 2006. @article{Shin2006,
title = {Observation of Phase Separation in a Strongly Interacting Imbalanced Fermi Gas},
author = {Y Shin and M W Zwierlein and C H Schunck and A Schirotzek and W Ketterle},
year = {2006},
date = {2006-01-01},
journal = {Physical Review Letters},
volume = {97},
pages = {30401},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
|
2005
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Schunck, C H; Zwierlein, M W; Stan, C A; Raupach, S M F; Ketterle, W; Simoni, A; Tiesinga, E; Williams, C J; Julienne, P S Feshbach resonances in fermionic Li6 Journal Article In: Physical Review A - Atomic, Molecular, and Optical Physics, vol. 71, no. 4, 2005, ISSN: 10502947 10941622. @article{Schunck2005,
title = {Feshbach resonances in fermionic Li6},
author = {C H Schunck and M W Zwierlein and C A Stan and S M F Raupach and W Ketterle and A Simoni and E Tiesinga and C J Williams and P S Julienne},
doi = {10.1103/PhysRevA.71.045601},
issn = {10502947 10941622},
year = {2005},
date = {2005-01-01},
journal = {Physical Review A - Atomic, Molecular, and Optical Physics},
volume = {71},
number = {4},
abstract = {Feshbach resonances in Li6 were experimentally studied and theoretically analyzed. In addition to two previously known s-wave resonances, three p-wave resonances were found. Four of these resonances are narrow and yield a precise value of the singlet scattering length. The position of the broad s-wave resonance near 83mT is mostly sensitive to the triplet potential. It was previously determined in a molecule-dissociation experiment for which we, here, discuss systematic shifts. ? 2005 The American Physical Society.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Feshbach resonances in Li6 were experimentally studied and theoretically analyzed. In addition to two previously known s-wave resonances, three p-wave resonances were found. Four of these resonances are narrow and yield a precise value of the singlet scattering length. The position of the broad s-wave resonance near 83mT is mostly sensitive to the triplet potential. It was previously determined in a molecule-dissociation experiment for which we, here, discuss systematic shifts. ? 2005 The American Physical Society. |
Zwierlein, M W; Schunck, C H; Stan, C A; Raupach, S M F; Ketterle, W Formation dynamics of a fermion pair condensate Journal Article In: Physical Review Letters, vol. 94, no. 18, 2005, ISSN: 00319007 10797114. @article{Zwierlein2005b,
title = {Formation dynamics of a fermion pair condensate},
author = {M W Zwierlein and C H Schunck and C A Stan and S M F Raupach and W Ketterle},
doi = {10.1103/PhysRevLett.94.180401},
issn = {00319007 10797114},
year = {2005},
date = {2005-01-01},
journal = {Physical Review Letters},
volume = {94},
number = {18},
abstract = {The dynamics of pair condensate formation in a strongly interacting Fermi gas close to a Feshbach resonance was studied. We employed a phase-shift method in which the delayed response of the many-body system to a modulation of the interaction strength was recorded. The observable was the fraction of condensed molecules in the cloud after a rapid magnetic field ramp across the Feshbach resonance. The measured response time was slow compared to the rapid ramp, which provides final proof that the molecular condensates reflect the presence of fermion pair condensates before the ramp. ? 2005 The American Physical Society.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The dynamics of pair condensate formation in a strongly interacting Fermi gas close to a Feshbach resonance was studied. We employed a phase-shift method in which the delayed response of the many-body system to a modulation of the interaction strength was recorded. The observable was the fraction of condensed molecules in the cloud after a rapid magnetic field ramp across the Feshbach resonance. The measured response time was slow compared to the rapid ramp, which provides final proof that the molecular condensates reflect the presence of fermion pair condensates before the ramp. ? 2005 The American Physical Society. |
Zwierlein, M W; Abo-Shaeer, J R; Schirotzek, A; Schunck, C H; Ketterle, W Vortices and superfluidity in a strongly interacting Fermi gas Journal Article In: Nature, vol. 435, pp. 1047–1051, 2005. @article{Zwierlein2005,
title = {Vortices and superfluidity in a strongly interacting Fermi gas},
author = {M W Zwierlein and J R Abo-Shaeer and A Schirotzek and C H Schunck and W Ketterle},
year = {2005},
date = {2005-01-01},
journal = {Nature},
volume = {435},
pages = {1047--1051},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
|
2004
|
Zwierlein, M W; Stan, C A; Schunck, C H; Raupach, S M F; Kerman, A J; Ketterle, W Condensation of Pairs of Fermionic Atoms near a Feshbach Resonance Journal Article In: Physical Review Letters, vol. 92, pp. 120403, 2004. @article{Zwierlein2004,
title = {Condensation of Pairs of Fermionic Atoms near a Feshbach Resonance},
author = {M W Zwierlein and C A Stan and C H Schunck and S M F Raupach and A J Kerman and W Ketterle},
year = {2004},
date = {2004-01-01},
journal = {Physical Review Letters},
volume = {92},
pages = {120403},
abstract = {We have observed Bose-Einstein condensation of pairs of fermionic atoms in an ultracold $^6$Li gas at magnetic fields above a Feshbach resonance, where no stable 6Li2 molecules would exist in vacuum. We accurately determined the position of the resonance to be 822$pm$3 G. Molecular Bose-Einstein condensates were detected after a fast magnetic field ramp, which transferred pairs of atoms at close distances into bound molecules. Condensate fractions as high as 80% were obtained. The large condensate fractions are interpreted in terms of preexisting molecules which are quasistable even above the two-body Feshbach resonance due to the presence of the degenerate Fermi gas.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
We have observed Bose-Einstein condensation of pairs of fermionic atoms in an ultracold $^6$Li gas at magnetic fields above a Feshbach resonance, where no stable 6Li2 molecules would exist in vacuum. We accurately determined the position of the resonance to be 822$pm$3 G. Molecular Bose-Einstein condensates were detected after a fast magnetic field ramp, which transferred pairs of atoms at close distances into bound molecules. Condensate fractions as high as 80% were obtained. The large condensate fractions are interpreted in terms of preexisting molecules which are quasistable even above the two-body Feshbach resonance due to the presence of the degenerate Fermi gas. |
Stan, C A; Zwierlein, M W; Schunck, C H; Raupach, S M F; Ketterle, W Observation of Feshbach Resonances between Two Different Atomic Species Journal Article In: Physical Review Letters, vol. 93, pp. 143001, 2004. @article{Stan2004,
title = {Observation of Feshbach Resonances between Two Different Atomic Species},
author = {C A Stan and M W Zwierlein and C H Schunck and S M F Raupach and W Ketterle},
year = {2004},
date = {2004-01-01},
journal = {Physical Review Letters},
volume = {93},
pages = {143001},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
|
2003
|
Hadzibabic, Z; Gupta, S; Stan, C A; Schunck, C H; Zwierlein, M W; Dieckmann, K; Ketterle, W Fifty-fold improvement in the number of quantum degenerate fermionic atoms Journal Article In: Physical Review Letters, vol. 91, pp. 160401, 2003. @article{Hadzibabic2003,
title = {Fifty-fold improvement in the number of quantum degenerate fermionic atoms},
author = {Z Hadzibabic and S Gupta and C A Stan and C H Schunck and M W Zwierlein and K Dieckmann and W Ketterle},
year = {2003},
date = {2003-01-01},
journal = {Physical Review Letters},
volume = {91},
pages = {160401},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
|
Zwierlein, M W; Stan, C A; Schunck, C H; Raupach, S M F; Gupta, S; Hadzibabic, Z; Ketterle, W Observation of Bose-Einstein Condensation of Molecules Journal Article In: Physical Review Letters, vol. 91, no. 25, 2003, ISSN: 00319007. @article{Zwierlein2003b,
title = {Observation of Bose-Einstein Condensation of Molecules},
author = {M W Zwierlein and C A Stan and C H Schunck and S M F Raupach and S Gupta and Z Hadzibabic and W Ketterle},
issn = {00319007},
year = {2003},
date = {2003-01-01},
journal = {Physical Review Letters},
volume = {91},
number = {25},
abstract = {Bose-Einstein condensation (BCS) of tightly bound pairs (molecules) to BCS superfluidity of Cooper pairs was observed. Condensates were observed after evaporative cooling at various magnetic fields between 720 and 820 G. The results show Bose-Einstein condensates of up to 900 000 molecules by evaporative cooling of a spin mixture of fermionic lithium atoms. This condensate realizes the limit of tightly bound fermion pairs in the crossover between BCS superfluidity and BCS.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Bose-Einstein condensation (BCS) of tightly bound pairs (molecules) to BCS superfluidity of Cooper pairs was observed. Condensates were observed after evaporative cooling at various magnetic fields between 720 and 820 G. The results show Bose-Einstein condensates of up to 900 000 molecules by evaporative cooling of a spin mixture of fermionic lithium atoms. This condensate realizes the limit of tightly bound fermion pairs in the crossover between BCS superfluidity and BCS. |
Gupta, S; Hadzibabic, Z; Zwierlein, M W; Stan, C A; Dieckmann, K; Schunck, C H; Kempen, E G M Van; Verhaar, B J; Ketterle, W Radio-frequency spectroscopy of ultracold fermions Journal Article In: Science, vol. 300, no. 5626, 2003, ISSN: 00368075. @article{Gupta2003b,
title = {Radio-frequency spectroscopy of ultracold fermions},
author = {S Gupta and Z Hadzibabic and M W Zwierlein and C A Stan and K Dieckmann and C H Schunck and E G M {Van Kempen} and B J Verhaar and W Ketterle},
doi = {10.1126/science.1085335},
issn = {00368075},
year = {2003},
date = {2003-01-01},
journal = {Science},
volume = {300},
number = {5626},
abstract = {Radio-frequency techniques were used to study ultracold fermions. We observed the absence of mean-field "clock" shifts, the dominant source of systematic error in current atomic clocks based on bosonic atoms. This absence is a direct consequence of fermionic antisymmetry. Resonance shifts proportional to interaction strengths were observed in a three-level system. However, in the strongly interacting regime, these shifts became very small, reflecting the quantum unitarity limit and many-body effects. This insight into an interacting Fermi gas is relevant for the quest to observe superfluidity in this system.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Radio-frequency techniques were used to study ultracold fermions. We observed the absence of mean-field "clock" shifts, the dominant source of systematic error in current atomic clocks based on bosonic atoms. This absence is a direct consequence of fermionic antisymmetry. Resonance shifts proportional to interaction strengths were observed in a three-level system. However, in the strongly interacting regime, these shifts became very small, reflecting the quantum unitarity limit and many-body effects. This insight into an interacting Fermi gas is relevant for the quest to observe superfluidity in this system. |
Zwierlein, M W; Hadzibabic, Z; Gupta, S; Ketterle, W Spectroscopic Insensitivity to Cold Collisions in a Two-State Mixture of Fermions Journal Article In: Physical Review Letters, vol. 91, no. 25, 2003, ISSN: 00319007. @article{Zwierlein2003a,
title = {Spectroscopic Insensitivity to Cold Collisions in a Two-State Mixture of Fermions},
author = {M W Zwierlein and Z Hadzibabic and S Gupta and W Ketterle},
issn = {00319007},
year = {2003},
date = {2003-01-01},
journal = {Physical Review Letters},
volume = {91},
number = {25},
abstract = {The absence of the mean-field shift of radio frequency transitions in a fully decohered, interacting binary mixture of fermions was demonstrated. This was explained by proving the invariance of the interaction energy under coherent Hilbert space rotations. The absence of mean-field energy in a purely coherent superposition state. The results show that there is no spectroscopic shift even after decoherence has led to measurable mean-field energies.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The absence of the mean-field shift of radio frequency transitions in a fully decohered, interacting binary mixture of fermions was demonstrated. This was explained by proving the invariance of the interaction energy under coherent Hilbert space rotations. The absence of mean-field energy in a purely coherent superposition state. The results show that there is no spectroscopic shift even after decoherence has led to measurable mean-field energies. |
2002
|
Hadzibabic, Z; Stan, C A; Dieckmann, K; Gupta, S; Zwierlein, M W; Goerlitz, A; Ketterle, W Two species mixture of quantum degenerate Bose and Fermi gases Journal Article In: Physical Review Letters, vol. 88, pp. 160401, 2002. @article{Hadzibabic2002a,
title = {Two species mixture of quantum degenerate Bose and Fermi gases},
author = {Z Hadzibabic and C A Stan and K Dieckmann and S Gupta and M W Zwierlein and A Goerlitz and W Ketterle},
year = {2002},
date = {2002-01-01},
journal = {Physical Review Letters},
volume = {88},
pages = {160401},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
|