Nanotechnology Now

Our NanoNews Digest Sponsors



Heifer International

Wikipedia Affiliate Button


android tablet pc

Home > Press > Stirring-up atomtronics in a quantum circuit: What's so 'super' about this superfluid

Cover of Nature highlighting this research, courtesy of Nature Press Office. Image credit, Edwards/JQI
Cover of Nature highlighting this research, courtesy of Nature Press Office.

Image credit, Edwards/JQI

Abstract:
Atomtronics is an emerging technology whereby physicists use ensembles of atoms to build analogs to electronic circuit elements. Modern electronics relies on utilizing the charge properties of the electron. Using lasers and magnetic fields, atomic systems can be engineered to have behavior analogous to that of electrons, making them an exciting platform for studying and generating alternatives to charge-based electronics.

Stirring-up atomtronics in a quantum circuit: What's so 'super' about this superfluid

College Park, MD | Posted on February 12th, 2014

Using a superfluid atomtronic circuit, JQI physicists, led by Gretchen Campbell, have demonstrated a tool that is critical to electronics: hysteresis. This is the first time that hysteresis has been observed in an ultracold atomic gas. This research is published in the February 13 issue of Nature magazine, whose cover features an artistic impression of the atomtronic system.

Lead author Stephen Eckel explains, "Hysteresis is ubiquitous in electronics. For example, this effect is used in writing information to hard drives as well as other memory devices. It's also used in certain types of sensors and in noise filters such as the Schmitt trigger." Here is an example demonstrating how this common trigger is employed to provide hysteresis. Consider an air-conditioning thermostat, which contains a switch to regulate a fan. The user sets a desired temperature. When the room air exceeds this temperature, a fan switches on to cool the room. When does the fan know to turn off? The fan actually brings the temperature lower to a different set-point before turning off. This mismatch between the turn-on and turn-off temperature set-points is an example of hysteresis and prevents fast switching of the fan, which would be highly inefficient.

In the above example, the hysteresis is programmed into the electronic circuit. In this research, physicists observed hysteresis that is an inherent natural property of a quantum fluid. 400,000 sodium atoms are cooled to condensation, forming a type of quantum matter called a Bose-Einstein condensate (BEC), which has a temperature around 0.000000100 Kelvin (0 Kelvin is absolute zero). The atoms reside in a doughnut-shaped trap that is only marginally bigger than a human red blood cell. A focused laser beam intersects the ring trap and is used to stir the quantum fluid around the ring.

While BECs are made from a dilute gas of atoms less dense than air, they have unusual collective properties, making them more like a fluid—or in this case, a superfluid. What does this mean? First discovered in liquid helium in 1937, this form of matter, under some conditions, can flow persistently, undeterred by friction. A consequence of this behavior is that the fluid flow or rotational velocity around the team's ring trap is quantized, meaning it can only spin at certain specific speeds. This is unlike a non-quantum (classical) system, where its rotation can vary continuously and the viscosity of the fluid plays a substantial role.

Because of the characteristic lack of viscosity in a superfluid, stirring this system induces drastically different behavior. Here, physicists stir the quantum fluid, yet the fluid does not speed up continuously. At a critical stir-rate the fluid jumps from having no rotation to rotating at a fixed velocity. The stable velocities are a multiple of a quantity that is determined by the trap size and the atomic mass.

This same laboratory has previously demonstrated persistent currents and this quantized velocity behavior in superfluid atomic gases. Now they have explored what happens when they try to stop the rotation, or reverse the system back to its initial velocity state. Without hysteresis, they could achieve this by reducing the stir-rate back below the critical value causing the rotation to cease. In fact, they observe that they have to go far below the critical stir-rate, and in some cases reverse the direction of stirring to see the fluid return to the lower quantum velocity state.

Controlling this hysteresis opens up new possibilities for building a practical atomtronic device. For instance, there are specialized superconducting electronic circuits that are precisely controlled by magnetic fields and in turn, small magnetic fields affect the behavior of the circuit itself. Thus, these devices, called SQuIDs (superconducting quantum interference devices), are used as magnetic field sensors. "Our current circuit is analogous to a specific kind of SQuID called an RF-SQuID", says Campbell. "In our atomtronic version of the SQuID, the focused laser beam induces rotation when the speed of the laser beam "spoon" hits a critical value. We can control where that transition occurs by varying the properties of the "spoon". Thus, the atomtronic circuit could be used as an inertial sensor."

This two-velocity state quantum system has the ingredients for making a qubit. However, this idea has some significant obstacles to overcome before it could be a viable choice. Atomtronics is a young technology and physicists are still trying to understand these systems and their potential. One current focus for Campbell's team includes exploring the properties and capabilities of the novel device by adding complexities such as a second ring.

###

This research was supported by the NSF Physics Frontier Center at JQI.

####

For more information, please click here

Contacts:
Gretchen Campbell

Copyright © Joint Quantum Institute

If you have a comment, please Contact us.

Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.

Bookmark:
Delicious Digg Newsvine Google Yahoo Reddit Magnoliacom Furl Facebook

Related Links

"Hysteresis in a quantized superfluid ‘atomtronic’ circuit," S. Eckel, J.G. Lee, F. Jendrzejewski, N. Murray, C.W. Clark, C.J. Lobb, W.D. Phillips, M. Edwards, G.K. Campbell, Nature, 506, 200 (2014):

"Driving Phase Slips in a Superfluid Atom Circuit with a Rotating Weak Link," K.C. Wright, R.B. Blakestad, C.J. Lobb, W.D. Phillips, G.K. Campbell, Phys. Rev. Lett., 110, 060504 (2013):

"Observation of Persistent Flow of a Bose-Einstein Condensate in a Toroidal Trap," C. Ryu, M.F. Andersen, P. Cladé, V. Natarajan, K. Helmerson, W.D. Phillips, Phys. Rev. Lett., 99, (2007):

VIDEO: This is an animation showing a laser beam stirring a ring shaped quantum gas:

Related News Press

News and information

Researchers engineer improvements of technology used in digital memory November 24th, 2014

Research reveals how our bodies keep unwelcome visitors out of cell nuclei November 24th, 2014

An Inside Job: UC-Designed Nanoparticles Infiltrate, Kill Cancer Cells From Within November 24th, 2014

Cooling with the coldest matter in the world November 24th, 2014

Iran Exports Nanodrugs to Syria November 24th, 2014

Physics

Cooling with the coldest matter in the world November 24th, 2014

Researchers discern the shapes of high-order Brownian motions November 17th, 2014

Heat Transfer Sets the Noise Floor for Ultrasensitive Electronics November 11th, 2014

Measuring nano-vibrations November 5th, 2014

Videos/Movies

Purdue 3-D printing innovation capable of making stronger, lighter metal works for auto, aerospace industries November 20th, 2014

New way to move atomically thin semiconductors for use in flexible devices November 13th, 2014

Manipulating complex molecules by hand: New method in scanning probe microscopy: Jülich researchers create a word using 47 molecules November 6th, 2014

Measuring nano-vibrations November 5th, 2014

Superconductivity

Implementation of DNA Chains in Designing Nanospin Pieces November 9th, 2014

Molecular Nanotechnology

Researchers discern the shapes of high-order Brownian motions November 17th, 2014

Manipulating complex molecules by hand: New method in scanning probe microscopy: Jülich researchers create a word using 47 molecules November 6th, 2014

Measuring nano-vibrations November 5th, 2014

'Nanomotor lithography' answers call for affordable, simpler device manufacturing October 31st, 2014

Chip Technology

Nanometrics Announces Upcoming Investor Events November 19th, 2014

A novel method for identifying the body’s ‘noisiest’ networks November 19th, 2014

Researchers create & control spin waves, lifting prospects for enhanced info processing November 17th, 2014

VDMA Electronics Production Equipment: Growth track for 2014 and 2015 confirmed: Business climate survey shows robust industry sector November 14th, 2014

Quantum Computing

Pseudospin-driven spin relaxation mechanism in graphene November 11th, 2014

Heat Transfer Sets the Noise Floor for Ultrasensitive Electronics November 11th, 2014

Noise in a microwave amplifier is limited by quantum particles of heat November 10th, 2014

Sussex physicists find simple solution for quantum technology challenge October 28th, 2014

Sensors

Cooling with the coldest matter in the world November 24th, 2014

Canatu Launches CNB In-Mold Film for Transparent Touch on 3D Surfaces –in Cars, Household Appliances, Wearables, Portables November 20th, 2014

UO-industry collaboration points to improved nanomaterials: University of Oregon microscope puts spotlight on the surface structure of quantum dots for designing new solar devices November 20th, 2014

Spiraling light, nanoparticles and insights into life’s structure November 19th, 2014

Discoveries

Researchers engineer improvements of technology used in digital memory November 24th, 2014

Research reveals how our bodies keep unwelcome visitors out of cell nuclei November 24th, 2014

ASU, IBM move ultrafast, low-cost DNA sequencing technology a step closer to reality November 24th, 2014

An Inside Job: UC-Designed Nanoparticles Infiltrate, Kill Cancer Cells From Within November 24th, 2014

Announcements

Research reveals how our bodies keep unwelcome visitors out of cell nuclei November 24th, 2014

ASU, IBM move ultrafast, low-cost DNA sequencing technology a step closer to reality November 24th, 2014

An Inside Job: UC-Designed Nanoparticles Infiltrate, Kill Cancer Cells From Within November 24th, 2014

Cooling with the coldest matter in the world November 24th, 2014

Interviews/Book Reviews/Essays/Reports/Podcasts/Journals/White papers

Researchers engineer improvements of technology used in digital memory November 24th, 2014

Research reveals how our bodies keep unwelcome visitors out of cell nuclei November 24th, 2014

ASU, IBM move ultrafast, low-cost DNA sequencing technology a step closer to reality November 24th, 2014

An Inside Job: UC-Designed Nanoparticles Infiltrate, Kill Cancer Cells From Within November 24th, 2014

Photonics/Optics/Lasers

NRL Scientists Discover Novel Metamaterial Properties within Hexagonal Boron Nitride November 20th, 2014

Penn engineers efficiently 'mix' light at the nanoscale November 17th, 2014

'Direct writing' of diamond patterns from graphite a potential technological leap November 5th, 2014

Outsmarting Thermodynamics in Self-assembly of Nanostructures: Berkeley Lab reports method for symmetry-breaking in feedback-driven self-assembly of optical metamaterials November 4th, 2014

Quantum nanoscience

Cooling with the coldest matter in the world November 24th, 2014

Quantum mechanical calculations reveal the hidden states of enzyme active sites November 20th, 2014

Pseudospin-driven spin relaxation mechanism in graphene November 11th, 2014

Heat Transfer Sets the Noise Floor for Ultrasensitive Electronics November 11th, 2014

NanoNews-Digest
The latest news from around the world, FREE




  Premium Products
NanoNews-Custom
Only the news you want to read!
 Learn More
NanoTech-Transfer
University Technology Transfer & Patents
 Learn More
NanoStrategies
Full-service, expert consulting
 Learn More












ASP
Nanotechnology Now Featured Books




NNN

The Hunger Project







© Copyright 1999-2014 7th Wave, Inc. All Rights Reserved PRIVACY POLICY :: CONTACT US :: STATS :: SITE MAP :: ADVERTISE