News: Research Highlights

Tue January 1, 2008

Realization of a strongly interacting Bose-Fermi mixture from a two-component Fermi gas

Fermions are the fundamental building blocks of matter, whereas bosons emerge as composite particles. The simplest physical system to study the emergence of bosonic behavior is a two-component fermion mixture, where the composite boson is a dimer of the two different fermions.

News type:

Research Highlights

Tue January 1, 2008

High-Sensitivity diamond magnetometer with nanoscale resolution

J. M. Taylor, P. Cappellaro, L. Childress, L. Jiang, D. Budker, P. R. Hmmer, A. Yacoby, R. L. Walsworth, and M. D. Lukin, High-sensitivity diamond magnetometer with nanoscale resolution, Nature Physics 4, 810-816 (2008).

News type:

Research Highlights

Tue January 1, 2008

Magnetic trapping of atomic nitrogen and cotrapping of NH

M. T. Hummon, W. Campbell, H. Lu, Y. Wang, and J. M. Doyle, Magnetic trapping of atomic nitrogen and cotrapping of NH, Phys. Rev. Lett. 78, 050702 (2008).

News type:

Research Highlights

Tue January 1, 2008

Magnetic Sensing with an individual electronic spin in diamond

J. R. Maze, P. L. Stanwix, J. S. Hodges, S. Hong, J. M. Taylor, P. Cappellaro, L. Jiang, G. Dutt, E. Togan, A. S. Zibrov, A. Yacoby, R. L. Walsworth, and M. D. Lukin, Magnetic Sensing with an individual electronic spin in diamond, Nature 455, 644-647 (2008).

News type:

Research Highlights

Tue January 1, 2008

Microfabricated Ion Trap Systems for Quantum Simulations

We have developed and tested a generation of ion traps, for the purpose of quantum information science and quantum simulations. These traps are based on semiconductor lithography, fabricated at MIT, and operated at liquid helium temperature. The traps enable systematic study of the behavior of the quantum state of trapped ions, near the surface of...

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Research Highlights

Tue January 1, 2008

Magnetic trapping of silver and copper, and anomalous spin relaxation in the Ag-He system

M. T. Hummon, W. Campbell, H. Lu, Y. Wang, and J. M. Doyle, Magnetic trapping of atomic nitrogen and cotrapping of NH, Phys. Rev. Lett. 78, 050702 (2008).

News type:

Research Highlights

Tue January 1, 2008

Spin Squeezing on an Atomic Clock Transition

Atomic clocks, the most accurate instruments ever developed, can now operate at the Standard Quantum Limit; their uncertainty dominated by the uncorrelated projection of individual atoms into eigenstates. Using entanglement, quantum mechanics allows one to correlate the atoms so as to redistribute or squeeze such quantum noise, reducing the uncertainty in a variable of interest.

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Research Highlights

Mon January 1, 2007

Critical velocity for superfluid flow across the BEC-BCS crossover

One key property of a superfluid is the existence of a threshold (critical) velocity for dissipationless flow. Measuring this critical velocity not only unambiguously illustrates the superfluidity of the system, but furthermore provides important insight about the excitation mechanisms that eventually cause the breakdown of superfluidity.

In this paper we report on the measurement of critical velocities in an ultracold superfluid Fermi gas. The experimental signature was very clear, an abrupt onset of dissipation, when the velocity of the moving lattice was increased past a critical value.

We determined critical velocities for variable atom-atom interactions magnetically tuned through the BEC-BCS crossover. Most quantities describing the system vary monotonically across the BEC-BCS crossover, whereas the critical velocity shows a pronounced peak on resonance, which was clearly confirmed by our experiment. The maximum in the value of the critical velocity is caused by the change of the dissipation mechanism (pair breaking vs. phonon excitation) On the BCS side, the pairs become fragile and break more easily, whereas on the BEC side, the pairs are stable, but now the lower velocity of sound determines the critical velocity for the onset of dissipation.

News type:

Research Highlights

Mon January 1, 2007