atomic, molecular, and optical physics

Rey

kdcadmin — Thu, 23 Mar 2023 18:24:18 +0000

Ana Maria Rey

Affiliations

Fellow of CTQM
Fellow of JILA
Adjoint Professor, Department of Physics, University of Colorado Boulder

Bio

My main research interest is ultracold atoms and molecules loaded in optical lattices, which are periodic trapping potentials created by illuminating the atoms and molecules with laser beams. Atoms in optical lattices are analogous to electrons in solid state crystals. Their big advantage is that these "artificial crystals of light" are perfectly clean and highly controllable. Therefore, they are ideal for exploring a whole range of fundamental phenomena that are extremely difficult — or impossible — to study in traditional condensed matter systems. My goal is to study how to control and manipulate these systems to engineer different quantum phases such as superfluids, insulators, quantum magnets, and topological matter. I plan to use them for understanding the physics of strongly correlated bosonic and fermionic systems and nonequilibrium phenomena. Additionally, I am interested in studying how to generate and manipulate entanglement in quantum systems for use in quantum information processing and precision measurements.

CTQM Role

CTQM Fellow

Research Category

atomic, molecular, and optical physics

quantum information science

arey@jilau1.colorado.edu

Phone

303-492-8089 (office)

Website

https://jila.colorado.edu/arey

Holland

kdcadmin — Wed, 15 Mar 2023 17:37:48 +0000

Murray Holland

Affiliations

Fellow of CTQM
Fellow of JILA
Professor, Department of Physics, University of Colorado Boulder

Bio

My research involves theoretical studies of Bose-Einstein condensation, including (1) the modes of oscillation, (2) the quantitative effect of interactions and loss processes, (3) the behavior of a condensate undergoing evaporative cooling, and (4) the thermodynamics of a small number of atoms. My future research interests include the damping processes of coherent excitations, quantum diffusion of the condensate phase, and new methods for treating quantum kinetic theory. I also investigate quantum optics, in which I study the properties of laser fields and their interaction with matter. My other interests include optical cavities and their interaction with atomic beams and quantum measurement theory.

CTQM Role

CTQM Fellow

Research Category

atomic, molecular, and optical physics

quantum information science

mholland@jila.colorado.edu

Phone

303-492-4172 (office)

Website

http://jila.colorado.edu/holland

Atomic, Molecular, and Optical Physics

kdcadmin — Thu, 09 Mar 2023 21:38:45 +0000

Atomic, Molecular, and Optical Physics kdcadmin Thu, 03/09/2023 - 2:38 pm

Atomic, molecular and optical physics research interests are on developing ways to dynamically manipulate, control and understand interacting atomic molecular and optical systems. The main goals are to use them as quantum simulators of solid state materials and high energy systems, as quantum information processors, and to engineer improved quantum devices and technologies such as ultra-precise atomic clocks and quantum sensors. Topics at the top of our research priorities are: orbital quantum magnetism, quantum metrology with many-body states, topological quantum matter and non-equilibrium open driven quantum systems.

CTQM Fellow(s)

Ana Maria Rey

Murray Holland

Magic Atom Theory

kdcadmin — Mon, 08 Dec 2014 18:34:30 +0000

Magic Atom Theory kdcadmin Mon, 12/08/2014 - 11:34 am

Quantum mechanical theory developed by CTQM Fellow Leo Radzihovsky and CU graduate student Xiao Yin provides a detailed description the quantum state of a strongly interacting and highly nonequilibrium BEC created by the Cornell and Jin groups.

Image Credit

Steve Burrows and Brad Baxley

In 2013, the Cornell and Jin groups created and studied an extremely strongly interacting Bose-Einstein condensate (BEC) of rubidium atoms (⁸⁵Rb). This BEC was short lived and far out of equilibrium. At the time the experimentalists wondered if this new BEC could be a quantum liquid because the quantum mechanical waves of these puffed-up atoms were rubbing up against each other and sliding past one another—like atoms do in liquids we are familiar with in everyday life.

This seminal experiment captured the attention of CU Physics Professor and CTQM Fellow Leo Radzihovsky, who had been developing a theory of ⁸⁵Rb for many years. Not surprisingly, Radzihovsky wanted to further develop the theory to explain what was really going on with the puffy ⁸⁵Rb atoms in the new experiment. Radzihovsky and CU graduate student Xiao Yin discovered that the quantum state (phase) of the strongly interacting atoms was much wilder and crazier than anyone expected.

The quantum state of the strongly interacting BEC was neither a gas nor a liquid. Rather, it was something altogether new that had properties of both. The ability of a strongly interacting gas of ⁸⁵Rb atoms to be both a gas and a liquid at the same time is purely quantum mechanical and has no analog in ordinary life.

An even more significant accomplishment was that the new theory explained why a strongly interacting BEC behaves they way it does. For example, it confirmed the experimental observation of the evolution of strongly interacting ⁸⁵Rb atoms into a non-equilibrium steady state. It also described specific characteristics of the strongly interacting BEC such as the distribution of its momentum (including its long tail). And, the theorists were recently able to identify the Contact via an analysis of this momentum distribution. Although the Contact was predicted to appear in ultracold gases under conditions when the atoms are close “contact” in a BEC, it has not been observed in the Cornell-Jin experiment.

Radzihovsky and Yin recently completed additional work on strongly interacting BECs, including an analysis of the RF spectroscopy used in the experiment and a deeper look into the behavior of the system (e.g., its excitation energy) as it evolves. In the future, they plan to continue to study the evolution of the strongly interacting BEC system from the time it is created until the BEC disappears as the ⁸⁵Rb atoms form molecules.

Principal Investigators

Leo Radzihovsky

Research Topics

atomic, molecular, and optical physics

Exciting Adventures in Coupling

kdcadmin — Fri, 26 Sep 2014 17:31:27 +0000

Exciting Adventures in Coupling kdcadmin Fri, 09/26/2014 - 11:31 am

According to new theory by the Gurarie and Rey groups, dipole-dipole interactions between ultracold polar molecules pinned in an optical lattice can make the molecules swap their internal rotational state (spin) at the cost of inducing a net spin current across the lattice. This elaborate spin swapping, which affects molecule motion or circulation, is known as spin-orbit coupling.

Image Credit

The Rey group and Steve Burrows

New theory describing the spin behavior of ultracold polar molecules is opening the door to explorations of exciting, new physics. According to the Gurarie and Rey theory groups, ultracold dipolar molecules can do even more interesting things than swapping spins. For instance, spin swapping occurs naturally when ultracold potassium-rubidium (KRb) molecules are in two of their four possible excited and ground states. The differences in two states are sufficient to cause a spinning molecule to slow down at the same time another molecule begins to rotate.

The exciting news is that when two KRb molecules are in three of the four possible states, they don’t just swap their spins. The direction of the spin in the molecule that starts rotating gets reversed! This more elaborate spin swapping affects the motion of the molecules, a phenomenon known as spin-orbit coupling.

Spin-orbit coupling is something that happens in solids when electrons move inside the electric field of a crystal. This process is the key to understanding spin transport and spin currents, which are analogs of electron transport and electric currents. Spin-orbit coupling also plays a role in some very exotic phenomena such as the creation of a Majorana particle, which is its own antiparticle!

The theorists responsible for discovering these exciting new adventures in spin-orbit coupling are research associates Sergey Syzranov and Michael Wall, CU Associate Professor of Physics Victor Gurarie, and CU Associate Research Professor of Physics Ana Maria Rey. Guarie and Rey are CTQM Fellows. Their discovery of spin-orbit coupling in ultracold molecules was reported online in Nature Communications on November 7, 2014.

The next step in this research is finding a model system for learning how to implement and control spin-orbit coupling. And, ultracold polar-molecule experiments are ideally suited for this purpose. For example, ultracold KRb molecules are polar, which means that the K end of one molecule attracts the Rb end of another molecule, while two K ends or two Rb ends repel each other. These behaviors are known as dipole-dipole interactions. The new theory predicts that dipole-dipole interactions will spontaneously give rise to spin-orbit coupling in an ultracold gas of polar molecules.

“The nice part is that with cold molecules, spin-orbit coupling just exists,” Rey explained. “We don’t need to zap anything with a laser to create it.”

Rey and her collaborators predict that spin-orbit coupling in ultracold polar molecules will generate excitations called chirons. Chirons are similar to the quasi particles found in bilayer graphene. They are expected to show up in the spin behaviors, spin currents, and spin interactions that occur in an ensemble of ultracold polar molecules pinned inside a deep optical lattice (a crystal of light created by intersecting laser beams). In other words, just about everything predicted by the new theory could soon be tested in the ultracold molecule laboratory in JILA!

Principal Investigators

Ana Maria Rey

Victor Gurarie

Research Topics

atomic, molecular, and optical physics

Atoms, Atoms, Frozen Tight in the Crystals of the Light, What Immortal Hand or Eye Could Frame Thy Fearful Symmetry?

kdcadmin — Mon, 18 Aug 2014 17:21:59 +0000

Atoms, Atoms, Frozen Tight in the Crystals of the Light, What Immortal Hand or Eye Could Frame Thy Fearful Symmetry? kdcadmin Mon, 08/18/2014 - 11:21 am

Strontium atoms in a quantum simulator display SU(N≤10) symmetry because of having 10 different nuclear spin states that are decoupled from their electronic and motional states. This symmetry was predicted by the Rey group and recently observed by the Ye group.

Image Credit

The Ye and Rey groups, and Steve Burrows

Symmetries described by SU(N) group theory made it possible for physicists in the 1950s to explain how quarks combine to make protons and neutrons and JILA theorists in 2013 to model the behavior of atoms inside a laser. Now, the Ye group has observed a manifestation of SU(N≤10) symmetry in the magnetic behavior of strontium-87 (⁸⁷Sr) atoms trapped in crystals of light created by intersecting laser beams inside a quantum simulator (originally developed as an optical atomic clock).

This first-ever spectroscopic observation of SU(N) orbital magnetism in ⁸⁷Sr atoms cooled to micro-Kelvin temperatures was reported online in Science Express on August 21, 2014.

Several advances made this observation possible: (1) Seminal theory work by the Rey group predicting the magnetic behavior of ⁸⁷Sr atoms at cold and ultracold temperatures; (2) Exquisite measurement precision available from an ultrastable laser developed for the ⁸⁷Sr-lattice optical atomic clock; (3) The ability to freeze out the motional states of the atoms, but preserve the flow of information, at relatively “high” μK temperatures; (3) The use of ⁸⁷Sr atoms, whose 10 nuclear spin states are decoupled from their interparticle interactions; and (4) The experimental control of the number of ⁸⁷Sr atoms in the ground and excited electronic states used as orbitals.

This groundbreaking work opens the door to (1) precision studies of collisions between nearly identical ⁸⁷Sr atoms that differ only in the states of their nuclear spins, (2) a deeper understanding of the role of atomic orbitals in collisions and chemical reactions, and (3) investigations of quantum magnetism and exotic materials. For instance, theorists have predicted that a chiral spin liquid will form if ⁸⁷Sr atoms are prepared in all 10 nuclear spin states and cooled down in a two-dimensional lattice (crystal of light). This exotic substance has no apparent order even at ultralow temperatures approaching absolute zero!

The researchers responsible for launching this new, exciting work include research associate Xibo Zhang, graduate students Mike Bishof and Sarah Bromley, research associate Christina Krauss and Professor Peter Zoller of the University of Innsbruck (Austria), Professor Marianna Safronova of the University of Delaware as well as CU Associate Research Professor of Physics Ana Maria Rey and CU Professor of Physics Adjoint Jun Ye. Rey is a CTQM Fellow.

Principal Investigators

Ana Maria Rey

Research Topics

atomic, molecular, and optical physics

Dealing with Loss

kdcadmin — Wed, 05 Mar 2014 18:06:21 +0000

Dealing with Loss kdcadmin Wed, 03/05/2014 - 11:06 am

By continuously measuring ultracold KRb molecules in tubes (with weak lattices) created by intersecting laser beams, researchers suppress the loss of the molecules during experiments. The loss suppression is due to the quantum Zeno effect.

Image Credit

The Ultracold Molecule Collaboration and Brad Baxley,

There’s exciting news from JILA’s ultracold molecule collaboration. The Jin, Ye, Holland, and Rey groups have come up with new theory (verified by experiment) that explains the suppression of chemical reactions between potassium-rubidium (KRb) molecules in the KRb quantum simulator. The main reason the molecules do not collide and react is continuous measurement of molecule loss from the simulator. That it works this way is a consequence of the quantum Zeno effect, also known as the watched pot effect, as in the proverb “A watched pot never boils.”

In essence, if researchers investigate a quantum system by continuously measuring it, things stop changing altogether. The strange laws of quantum mechanics are responsible for this odd behavior. These laws dictate that the act of measurement itself forces the KRb molecules into a particular quantum state. And, if measurements occur continuously, the molecules will stay in that state because the measurements themselves are collectively preventing any change in the quantum states of the molecules. The idea that continuous measurements prevent a quantum system from evolving is the essence of the quantum Zeno effect, named for the Greek philosopher Zeno of Elea.

Thus, if you adjust a quantum simulator so that (according to the laws of classical physics) the molecules inside it get lost faster and faster because of colliding and reacting, then the laws of quantum mechanics will actually make the molecules react slower and slower until they eventually just sit there forever and never get lost. It’s almost as if two KRb molecules “know” from the continuous measurements not to hop into the same place in the simulator because they would react and disappear if they did. New theory by the Holland and Rey groups shows explicitly how this works. It not only verifies the quantum Zeno effect, but also demonstrates that older theories that attempted to explain this kind of quantum behavior incorrectly predicted loss to happen five times faster.

In practical terms, the previous and less accurate theories suggested that the number of KRb molecules in the simulator would be about one molecule per two lattice sites (which are energy wells created by intersecting laser beams). In practice, however, that calculation predicted too many molecules. Right now, the number of KRb molecules in the simulator is fewer, typically one per every 10 lattice sites. And, this just happens to match the amount of lattice filling predicted by the new theory. Clearly, increasing the lattice filling is going be a lot harder than researchers originally expected it to be.

Untangling this complicated quantum behavior required the brainpower and dedication of 13 JILA researchers. The theory team comprised graduate student Bihui Zhu, recently minted Ph.D. Michael Foss-Feig, research associates Johannes Schachenmayer and Michael Wall, senior research associate Kaden Hazzard as well as CU Professor of Physics Murray Holland and CU Associate Research Professor of Physics Ana Maria Rey. Holland and Rey are CTQM Fellows. The experimental team included research associates Bryce Gadway and Bo Yan, graduate students Steven Moses and Jacob Covey, and Fellows Debbie Jin and Jun Ye.

Principal Investigators

Ana Maria Rey

Murray Holland

Research Topics

atomic, molecular, and optical physics

Quantum Legoland

kdcadmin — Mon, 01 Jul 2013 16:45:46 +0000

Quantum Legoland kdcadmin Mon, 07/01/2013 - 10:45 am

Artist’s concept of the quantum building blocks of a laser.

Image Credit

The Holland group and Brad Baxley

The quantum world is not quite as mysterious as we thought it was. It turns out that there are highways into understanding this strange universe. And, graduate students Minghui Xu and David Tieri with Fellow Murray Holland have just discovered one such superhighway that has been around since the 1950s. Traveling along this superhighway has made it possible to understand the quantum behavior of hundreds of atoms inside every laser used in JILA, including the superradiant laser in the Thompson lab that works entirely differently from all the others.

The weirdest thing is that this is the same superhighway traveled by the SU(4) group theory used to explain quark physics. Quarks are elementary particles that make up hadrons; hadrons are things like the protons and neutrons that sit inside every atomic nucleus. The lowest energy quarks are known as up, down, strange, and charm. And, as it turns out, up, down, strange, and charm quarks are analogs of the four basic “Lego building blocks” that also describe the quantum behavior of atoms in a laser.

So why is it so hard to figure out what’s happening with hundreds of atoms inside a laser? The answer is easy. It’s the fault of quantum mechanics and its mind-boggling complexity. A mere three hundred atoms, each with two possible states, have as many different combinations of quantum states as there are atoms in the entire Universe.

Fortunately, CTQM Fellow Murray Holland and graduate students Minghui Xu and David Tieri have just found a pathway through this complexity. This pathway exists because of something called invariance. Invariance is responsible for the familiar laws of conservation of energy and conservation of momentum that govern the classical world we are more familiar with. The two laws state that if no external forces are acting on a system, (1) the amount of energy remains constant over time and (2) an object will continue moving at the same speed forever. The fact that energy remains constant is due to the invariance of choosing the origin of time. The fact that an object just keeps going at the same speed is due to the invariance of choosing the origin of space.

As it turns out, the Holland group has just discovered an intricate invariance that governs the quantum physics of lasers. As “luck” would have it, only a relatively small number of possible quantum states are compatible with a particular value of the invariant quantity once it’s determined by a laser system itself.

It’s as if a laser can “choose” to be made of only one color such as red, blue, green, yellow, black, grey, or clear Legos. But, once decided, the laser obeys a conservation law that means that the color of the Lego blocks won’t change in time. The constancy of the color represents the invariance. Once the invariance is in place, one can make any state of a laser from just four shapes of quantum Lego blocks, a square (up), a corner piece (down), a thin arch piece (strange) and a rectangle (charm).

Of course, like quarks, the laser analogs (Lego shapes) are actually quantum mechanical states. But, it’s possible to construct quite complicated things from four elementary building blocks.

“We’ve got four types of blocks, and, out of them, we can make everything, Holland explains. “When you realize this, there is a clear path to an unbelievable reduction in complexity.”

Holland and his students have just proved this assertion in a new Physical Review A paper. In the paper, they showed how “quark physics” mathematics could be used to solve the quantum master equations for both ordinary and superradiant lasers, feats once considered impossible.

The new theory opens the door to finding ways to build even more complicated structures out of the basic four quantum Legos. Plus, new building blocks, such as laser analogs of the much heavier top and bottom quarks, may be found.

“We already know there are some optical systems where the building blocks are slightly different,” Holland says. “The questions are: How far can we push this new idea? Can we use our new theory to understand other important systems in quantum optics and ultracold gases?”

Perhaps an important question for the rest of us to ponder is: Without invariances, would we even have the world we know?

Principal Investigators

Murray Holland

Research Topics

atomic, molecular, and optical physics