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.]

ITAMP 2013 DAMOP presentations (Quebec City Canada)

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

Abstract: D1.00057 Deterministic Coupling of a Single Atom to a Nanoscale Optical Cavity

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

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)

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).