Wednesday, July 31, 2013

Binding together repelling atoms

Basic chemistry tells us that a bond between atoms can form if it is energetically more favorable for the atoms to stick together than staying apart. This fundamentally requires an attractive force between the atoms. However, new theoretical predictions show that the combination of a repelling force and controlled noise from an environment can also have the surprising effect of leading to a bound state, although one with quite exotic properties. The research team consisting of ITAMP postdoc Mikhail Lemeshko and former ITAMP postdoc Hendrik Weimer* report their results in the journal Nature Communications [1].

How is it possible that repulsion and noise, both two effects countering the formation of a chemical bond, can lead to a bound state nevertheless? To understand this, one has to take into account the quantum properties of the atoms: adding controlled noise to a quantum system can result in an interference phenomenon that traps the atoms in a well-defined quantum state. The repulsive force then ensures that this trapping occurs at a particular distance, which sets the length of the bond. The nature of the novel bound state is strikingly different from their chemical counterparts. For example, the bound state is remarkably robust and can hardly be broken by depositing a constant amount of energy to it.

Lemeshko and Weimer consider one of the most basic and universally available sources of noise: vacuum fluctuations of the electromagnetic field. In the past, the techniques making use of these quantum fluctuations have led to dramatic improvements in laser cooling, culminating in the results that were awarded the 1997 Nobel Prize in Physics. The authors believe that the first applications of the discovered binding mechanism might be in the area of cooling of atomic quantum gases.

*presently at the Institute for Theoretical Physics at Leibniz Universität Hannover, Germany

[1] M. Lemeshko, H. Weimer. Dissipative binding of atoms by non-conservative forces. Nature Communications 4, 2230 (2013).

[The attached figure shows the probability distribution of two atoms forming the novel bond. Red color indicating high probability occurs at lines of fixed distance between the atoms.]

Friday, May 17, 2013

ITAMP 2013 DAMOP presentations (Quebec City Canada)

James Babb
4:00 PM–4:00 PM, Tuesday, June 4, 2013
Room: 400A
Abstract: D1.00131 : Rydberg helium and the helium dimer: Relativistic and retardation effects
http://meeting.aps.org/Meeting/DAMOP13/Event/194145

Johannes Feist
4:00 PM–4:00 PM, Tuesday, June 4, 2013
Room: 400A
http://meeting.aps.org/Meeting/DAMOP13/Event/194071

Doerte Blume
4:00 PM–4:00 PM, Tuesday, June 4, 2013
Room: 400A
Abstract: D1.00061 : Thermodynamics of systems of aligned dipoles
http://meeting.aps.org/Meeting/DAMOP13/Event/194075



Doerte Blume
X.Y. Yin
4:00 PM–4:00 PM, Wednesday, June 5, 2013
Room: 400A
Abstract: K1.00046 : Energy spectra of small two-component Fermi gases in a cubic box with periodic boundary conditions
http://meeting.aps.org/Meeting/DAMOP13/Event/194392

Doerte Blume
Seyed Ebrahim Gharashi
3:00 PM–3:12 PM, Thursday, June 6, 2013
Room: 200A 
Abstract: P1.00003 : Correlations of the metastable branch of harmonically-trapped one-dimensional two-component Fermi gases
http://meeting.aps.org/Meeting/DAMOP13/Event/194605

Doerte Blume
Yangqian Yan 
4:00 PM–4:00 PM, Thursday, June 6, 2013
Room: 400A
Abstract:Q1.00048 : Finite-temperature properties of small trapped two-component Fermi gases: Tan contact and statistics
http://meeting.aps.org/Meeting/DAMOP13/Event/194718

Doerte Blume
Janine Shertzer
10:30 AM–12:30 PM, Friday, June 7, 2013
Room: 303
Abstract: U7.00006 : Scattering properties of three ultracold atoms in a cylindrical waveguide geometry
11:30 AM–11:42 AM
http://meeting.aps.org/Meeting/DAMOP13/Event/194915

Doerte Blume
Arghavan Safavi 
Seth Rittenhouse 
Hossein Sadeghpour
10:30 AM–12:30 PM, Friday, June 7, 2013
Room: 303
Abstract: U7.00007 : Non-universal bound states of two identical heavy fermions and one light particle
http://meeting.aps.org/Meeting/DAMOP13/Event/194916

Tony Lee
Sarang Gopalakrishnan
Mikhail Lukin 
 8:00 AM–9:48 AM, Wednesday, June 5, 2013
Room: 204
Abstract: Dissipative phase transitions in anisotropic spin models
9:12 AM–9:24 AM
http://meeting.aps.org/Meeting/DAMOP13/Event/194201

Tony Lee 
Anzi Hu
Charles Clark
10:30 AM–12:30 PM, Wednesday, June 5, 2013
Room: 202
Abstract: H3.00007 : Long-range spatial correlations in a driven-dissipative system of Rydberg atoms
11:42 AM–11:54 AM
http://meeting.aps.org/Meeting/DAMOP13/Event/194255

Mikhail Lemeshko
Hendrik Weimer 
2:00 PM–4:00 PM, Wednesday, June 5, 2013
Room: 202
Abstract: J3.00006 : Dissipative binding of atoms by non-conservative forces
3:00 PM–3:12 PM
http://meeting.aps.org/Meeting/DAMOP13/Event/194314

Mikhail Lemeshko
Satyan Bhongale
Ludwig Mathey 
Erhai Zhao 
Susanne Yelin 
10:30 AM–12:30 PM, Thursday, June 6, 2013
Room: 200B
Abstract:  N2.00008 : Quantum phases of quadrupolar Fermi gases in optical lattices
11:54 AM–12:06 PM
http://meeting.aps.org/Meeting/DAMOP13/Event/194553

Charles Mathy
Michael Knap
Eugene Demler
 10:30 AM–12:06 PM, Thursday, June 6, 2013
Room: 202
Abstract: Quantum flutter versus Bloch oscillations in one-dimensional quantum liquids out of equilibrium
10:42 AM–10:54 AM
http://meeting.aps.org/Meeting/DAMOP13/Event/194558

Swati Singh
Steven Steinke
Pierre Meystre
Keith Schwab 
Mukund Vengalattore 
10:30 AM–12:06 PM, Tuesday, June 4, 2013
Room: 202
Abstract: B3.00007 : Measurement backaction on a spinor condensate from off-resonant light
11:42 AM–11:54 AM
http://meeting.aps.org/Meeting/DAMOP13/Event/193908

Swati Singh
Adi Pick
Mikhail D. Lukin
Susanne F. Yelin 
 8:00 AM–9:24 AM, Friday, June 7, 2013
Room: 302
Abstract:T6.00003 : Cooling of Nuclear Spins in Diamond via Dark State Spectroscopy
8:24 AM–8:36 AM
http://meeting.aps.org/Meeting/DAMOP13/Event/194846

Arghavan Safavi-Naini
Barbara Capogrosso-Sansone
Anatoly Kuklov 
2:00 PM–4:00 PM, Wednesday, June 5, 2013
Room: 200B
Abstract: J2.00001 : Strongly interacting quantum phases of polarized dipolar bosons in multi-layered optical lattice
2:00 PM–2:12 PM
http://meeting.aps.org/Meeting/DAMOP13/Event/194298

Arghavan Safavi
Seth Rittenhouse
Dorte Blume 
Hossein Sadeghpour 
10:30 AM–12:30 PM, Friday, June 7, 2013
Room: 303
Abstract: U7.00007 : Non-universal bound states of two identical heavy fermions and one light particle
11:42 AM–11:54 AM
http://meeting.aps.org/Meeting/DAMOP13/Event/194916

Janine Shertzer
Aaron Temkin
  4:00 PM–4:00 PM, Wednesday, June 5, 2013
Room: 400A
Abstract: K1.00131 : Electron scattering from excited states of H: derivation of the ionization threshold law
http://meeting.aps.org/Meeting/DAMOP13/Event/194477

Janine Shertzer 
Doerte Blume
 10:30 AM–12:30 PM, Friday, June 7, 2013
Room: 303
Abstract: U7.00006 : Scattering properties of three ultracold atoms in a cylindrical waveguide geometry
11:30 AM–11:42 AM
http://meeting.aps.org/Meeting/DAMOP13/Event/194915

Friday, April 19, 2013

Quadrupolar atoms and molecules as a new platform to study many-body physics

The ongoing quest on achieving high-density samples of dipolar atoms and molecules aims at observing the exciting many-body phenomena predicted in such systems [1].

In the recent article in Physical Review Letters [2], the authors from ITAMP, George Mason University, and the University of Hamburg, introduced an alternative platform for quantum simulation of many-body systems. The proposed setup is based on nonspherical atoms or molecules with zero dipole moments but possessing a significant value of electric quadrupole moments.

Considering a quadrupolar Fermi gas trapped in a 2D square optical lattice, the authors showed that the peculiar symmetry and broad tunability of the quadrupole-quadrupole interaction results in a rich phase diagram encompassing unconventional BCS and charge density wave phases, and opens up a perspective to create a topological superfluid.

Quadrupolar species, such as metastable alkaline-earth atoms and homonuclear molecules, are stable against chemical reactions and collapse and are readily available in experiment at higher densities compared to the dipolar atoms and molecules.




[1] T. Lahaye et al., Rep. Prog. Phys. 72, 126401 (2009); M. Baranov, Phys. Rep. 464, 71 (2008)

[2] S. G. Bhongale, L. Mathey, E. Zhao, S. F. Yelin, M. Lemeshko, Phys. Rev. Lett. 110, 155301 (2013)

Friday, February 8, 2013

Collective Qubits Compute Faster

Quantum computers can solve certain problems much faster than their classical counterparts, but their realization on a scale relevant for practical applications has proven to be very difficult. However, this could change with a new method for solid state quantum computers devised at ITAMP. We report our results in the journal Physical Review Letters.

While controlling single quantum bits ("qubits") is nowadays possible with high precision, the realization of large networks with many qubits remains an outstanding challenge. This is particularly relevant for devices based on magnetic impurities in solid state systems, where the magnetic interaction between the qubits is too weak. However, the research team could now show that this obstacle could be solved by grouping about 100 impurities to form a single collective qubit. When an external magnetic field is chosen correctly, the magnetic properties of the impurities lose their individual characteristics and become indistinguishable due to their quantum nature. Such collective quantum states are known to show drastically increased interaction strengths, allowing to perform faster quantum logic operations between the collective qubits.

While the proposed method is applicable for a large class of solid state qubits, the scientists present a detailed analysis for nitrogen-vacancy defect centers in diamond, demonstrating the realizability of much larger quantum networks. As few as 50 collective qubits are sufficient for immediate applications in the simulation of strongly correlated quantum systems.

Reference: Hendrik Weimer, Norman Y. Yao, Mikhail D. Lukin. Collectively enhanced interactions in solid-state spin qubits, Physical Review Letters 110, 067601 (2013).

Tuesday, August 7, 2012

ICAP 2012

This year the International Conference on Atomic Physics was hosted by École Polytechnique in Palaiseau near Paris, France.

Misha Lemeshko presented a poster "Dynamically engineering strongly-interacting phases in ultracold dipolar gases" [pdf], describing his recent work in collaboration with Hendrik Weimer and Roman Krems.

Monday, July 16, 2012

Building a crystal out of quantum bricks

Preparation of strongly interacting many-body phases starting from a weakly interacting quantum gas is known to be very challenging. It involves crossing a phase transition, where the energy gap protecting the ground state becomes vanishingly small for large systems. In a recent publication in Physical Review Letters, we report on a recipe to overcome this problem. In our work, we study the formation of dipolar spin crystals of ultracold polar molecules trapped in an optical lattice. We demonstrate that one can achieve a substantially better growth of the emergent spin crystal using non-adiabatic driving of rotational transitions.

Our proposed technique builds on the dipole blockade of microwave excitations. In the context of an effective spin-1/2 model, the dipole blockade allows to flip particular spins in an optical lattice without a need for single-site addressing. The growth of the spin crystal is started by a short sequence of microwave pulses that create a few flipped spins, serving as a nucleation center of the crystalline phase. After that, continuous microwave driving propagates the boundary of the crystal, adding one additional flipped spin after the other.

We investigate the dynamics under the continuous driving and demonstrate that the growth of the ordered domains is efficient. The analysis of the imperfections and the required experimental parameters shows that structures consisting of more than 1,000 spins can be grown. The average size of the resulting domains scales substantially more favorable compared to the conventional adiabatic preparation.






Reference: Mikhail Lemeshko, Roman V. Krems, and Hendrik Weimer,
"Nonadiabatic Preparation of Spin Crystals with Ultracold Polar Molecules",
Phys. Rev. Lett. 109, 035301 (2012).


About the authors: Misha Lemeshko and Hendrik Weimer are the ITAMP Postdoctoral Fellows at the Harvard-Smithsonian Center for Astrophysics and Harvard Physics Department; Roman Krems is an Associate Professor of Chemistry at the University of British Columbia in Vancouver.

Wednesday, May 23, 2012

ITAMP 2012 DAMOP presentations (Orange County, California)

James Babb
10:30 AM-12:30 PM, Thursday, June 7, 2012
Room: Terrace
Abstract: N7.00006 : Long-range interactions between Mg atoms
11:30 AM–11:42 AM
http://meetings.aps.org/Meeting/DAMOP12/Event/171916

Johannes Feist
8:00 AM–10:00 AM, Wednesday, June 6, 2012
Room: Garden 1-2
Abstract: G4.00005 : Nanoplasmonic light field synthesis for isolated attosecond pulse generation

9:24 AM–9:36 AM
http://meetings.aps.org/Meeting/DAMOP12/Event/171477

Johannes Feist
4:00 PM–4:00 PM, Wednesday, June 6, 2012
Room: Royal Ballroom
Abstract: K1.00021 : Attosecond streaking of correlated two-electron transitions
http://meetings.aps.org/Meeting/DAMOP12/Event/171658

Adam Kirrander
4:00 PM–4:00 PM, Tuesday, June 5, 2012
Room: Royal Ballroom
Abstract: D1.00037 : Quantum dynamics in strong fields with Fermion Coupled Coherent States
 http://meetings.aps.org/Meeting/DAMOP12/Event/171332

Adam Kirrander
8:00 AM–10:00 AM, Thursday, June 7, 2012
Room: Garden 4
Abstract: M6.00007 : Theoretical Dynamics of Heavy Rydberg States in Rb$_2$
9:12 AM–9:24 AM
http://meetings.aps.org/Meeting/DAMOP12/Event/171850

Adam Kirrander
4:00 PM–4:00 PM, Thursday, June 7, 2012
Room: Royal Ballroom
Abstract: Q1.00009 : X-ray diffraction assisted spectroscopy of Rydberg states
http://meetings.aps.org/Meeting/DAMOP12/Event/171991



Mikhail Lemeshko
2:00 PM–4:00 PM, Wednesday, June 6, 2012
Room: Garden 3
Abstract: J5.00004 : Molecular interactions in and with fields: thermal collisions, ultracold gases, supersymmetry
3:30 PM–4:00 PM
http://meetings.aps.org/Meeting/DAMOP12/Event/171614

 Guin-Dar Lin
2:00 PM–4:00 PM, Tuesday, June 5, 2012
Room: Grand Ballroom GF
Abstract: C2.00010 : Cooling of particle ensembles with cooperative effects
3:48 PM–4:00 PM
http://meetings.aps.org/Meeting/DAMOP12/Event/171260

 
Jerome Loreau
8:00 AM–10:00 AM, Friday, June 8, 2012
Room: Garden 1-2
Abstract: T4.00007 : Non-reactive collisions of sodium and silver atoms with nitrogen molecules

9:12 AM–9:24 AM
http://meetings.aps.org/Meeting/DAMOP12/Event/172175
 
Charles Mathy
2:00 PM–4:00 PM, Thursday, June 7, 2012
Room: Garden 1-2
Abstract: P4.00005 : Quantum flutter of supersonic particles in one-dimensional quantum liquids

2:48 PM–3:00 PM
http://meetings.aps.org/Meeting/DAMOP12/Event/171944

Roberto Onofrio 
10:30 AM–12:30 PM, Wednesday, June 6, 2012
Room: Grand Ballroom E
Abstract: H3.00004 : Angular momentum changing transitions in proton-Rydberg hydrogen atom collisions

11:06 AM–11:18 AM
http://meetings.aps.org/Meeting/DAMOP12/Event/171529

Seth Rittenhouse
4:00 PM–4:00 PM, Tuesday, June 5, 2012
Room: Royal Ballroom
Abstract: D1.00122 : Theoretical and Experimental evidence for the observation of trilobite states in Cs
http://meetings.aps.org/Meeting/DAMOP12/Event/171417

Seth Rittenhouse
 8:00 AM–10:00 AM, Thursday, June 7, 2012
Room: Garden 4
Abstract: M6.00005 : Homonuclear cesium Rydberg molecules
8:48 AM–9:00 AM
http://meetings.aps.org/Meeting/DAMOP12/Event/171848

Seth Rittenhouse
 10:30 AM–12:30 PM, Thursday, June 7, 2012
Room: Grand Ballroom GF
Abstract: N2.00003 : First order SF-MI transition in the Bose-Hubbard model with tunable three-body onsite interaction
10:54 AM–11:06 AM
http://meetings.aps.org/Meeting/DAMOP12/Event/171859

H.R. Sadeghpour
0:30 AM–12:30 PM, Wednesday, June 6, 2012
Room: Grand Ballroom E
Abstract: H3.00004 : Angular momentum changing transitions in proton-Rydberg hydrogen atom collisions
11:06 AM–11:18 AM
http://meetings.aps.org/Meeting/DAMOP12/Event/171529

H.R. Sadeghpour
 8:00 AM–10:00 AM, Thursday, June 7, 2012
Room: Garden 4
Abstract: M6.00007 : Theoretical Dynamics of Heavy Rydberg States in Rb$_2$
9:12 AM–9:24 AM
http://meetings.aps.org/Meeting/DAMOP12/Event/171850


H.R. Sadeghpour
 2:00 PM–3:48 PM, Thursday, June 7, 2012
Room: Garden 4
Abstract: P6.00009 : An ab-initio model of anomalous heating in planar ion traps
3:36 PM–3:48 PM
http://meetings.aps.org/Meeting/DAMOP12/Event/171970

H.R. Sadeghpour
 8:00 AM–10:00 AM, Thursday, June 7, 2012
Room: Garden 4
Abstract: M6.00005 : Homonuclear cesium Rydberg molecules
8:48 AM–9:00 AM
http://meetings.aps.org/Meeting/DAMOP12/Event/171848

H.R. Sadeghpour
 2:00 PM–4:00 PM, Tuesday, June 5, 2012
Room: Terrace
Abstract: C7.00004 : Rydberg atom mediated polar molecule interactions
3:30 PM–4:00 PM
http://meetings.aps.org/Meeting/DAMOP12/Event/171294

H.R. Sadeghpour
 4:00 PM–4:00 PM, Tuesday, June 5, 2012
Room: Royal Ballroom
Abstract: D1.00122 : Theoretical and Experimental evidence for the observation of trilobite states in Cs
http://meetings.aps.org/Meeting/DAMOP12/Event/171417


Arghavan Safavi-Naini
 10:30 AM–12:30 PM, Thursday, June 7, 2012
Room: Grand Ballroom GF
Abstract: N2.00003 : First order SF-MI transition in the Bose-Hubbard model with tunable three-body onsite interaction
10:54 AM–11:06 AM
http://meetings.aps.org/Meeting/DAMOP12/Event/171859

Arghavan Safavi-Naini
 2:00 PM–3:48 PM, Thursday, June 7, 2012
Room: Garden 4
Abstract: P6.00009 : An ab-initio model of anomalous heating in planar ion traps
3:36 PM–3:48 PM
http://meetings.aps.org/Meeting/DAMOP12/Event/171970


Hendrik Weimer
8:00 AM–10:00 AM, Friday, June 8, 2012
Room: Grand Ballroom GF
Abstract: T2.00006 : Supersymmetry in Rydberg-dressed lattice fermions
9:00 AM–9:12 AM
http://meetings.aps.org/Meeting/DAMOP12/Event/172156

 Susanne Yelin
2:00 PM–4:00 PM, Tuesday, June 5, 2012
Room: Grand Ballroom GF
Abstract: C2.00010 : Cooling of particle ensembles with cooperative effects
3:48 PM–4:00 PM
http://meetings.aps.org/Meeting/DAMOP12/Event/171260

Susanne Yelin
 4:00 PM–4:00 PM, Wednesday, June 6, 2012
Room: Royal Ballroom
Abstract: K1.00066 : Theory of laser cooling of nuclear spins based on coherent population trapping
http://meetings.aps.org/Meeting/DAMOP12/Event/171703