Nanotechnology Now

Our NanoNews Digest Sponsors

Heifer International

Wikipedia Affiliate Button

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

Basque researchers turn light upside down February 23rd, 2018

Stiffness matters February 23rd, 2018

Imaging individual flexible DNA 'building blocks' in 3-D: Berkeley Lab researchers generate first images of 129 DNA structures February 22nd, 2018

'Memtransistor' brings world closer to brain-like computing: Combined memristor and transistor can process information and store memory with one device February 22nd, 2018

Superconductivity

Unconventional superconductor may be used to create quantum computers of the future: They have probably succeeded in creating a topological superconductor February 19th, 2018

Videos/Movies

Graphene on toast, anyone? Rice University scientists create patterned graphene onto food, paper, cloth, cardboard February 13th, 2018

Fast-spinning spheres show nanoscale systems' secrets: Rice University lab demonstrates energetic properties of colloids in spinning magnetic field February 7th, 2018

New research yields super-strong aluminum alloy January 25th, 2018

Piecework at the nano assembly line: Electric fields drive nano-motors a 100,000 times faster than previous methods January 22nd, 2018

Physics

Liquid crystal molecules form nano rings: Quantized self-assembly enables design of materials with novel properties February 7th, 2018

New exotic phenomena seen in photonic crystals: Researchers observe, for the first time, topological effects unique to an “open” system January 12th, 2018

Molecular Nanotechnology

Moving nanoparticles using light and magnetic fields January 25th, 2018

Piecework at the nano assembly line: Electric fields drive nano-motors a 100,000 times faster than previous methods January 22nd, 2018

'Gyroscope' molecules form crystal that's both solid and full of motion: New type of molecular machine designed by UCLA researchers could have wide-ranging applications in technology and science January 16th, 2018

Going swimmingly: Biotemplates breakthrough paves way for cheaper nanobots: By using bacterial flagella as a template for silica, researchers have demonstrated an easier way to make propulsion systems for nanoscale swimming robots November 30th, 2017

Chip Technology

Basque researchers turn light upside down February 23rd, 2018

Imaging individual flexible DNA 'building blocks' in 3-D: Berkeley Lab researchers generate first images of 129 DNA structures February 22nd, 2018

'Memtransistor' brings world closer to brain-like computing: Combined memristor and transistor can process information and store memory with one device February 22nd, 2018

Photonic chip guides single photons, even when there are bends in the road February 16th, 2018

Quantum Computing

Developing reliable quantum computers February 22nd, 2018

Unconventional superconductor may be used to create quantum computers of the future: They have probably succeeded in creating a topological superconductor February 19th, 2018

New silicon chip for helping build quantum computers and securing our information February 8th, 2018

Quantum algorithm could help AI think faster: Researchers in Singapore, Switzerland and the UK present a quantum speed-up for machine learning February 2nd, 2018

Sensors

Graphene on toast, anyone? Rice University scientists create patterned graphene onto food, paper, cloth, cardboard February 13th, 2018

Leti Chief Scientist Barbara De Salvo Will Help Kick Off ISSCC 2018 with Opening-Day Keynote: In Addition, Leti Scientists Will Present and Demo New Technology for Piezoelectric Energy Harvesting February 8th, 2018

Engineers develop flexible, water-repellent graphene circuits for washable electronics January 24th, 2018

Leti to Demo New Curving Technology at Photonics West that Improves Performance of Optical Components January 18th, 2018

Discoveries

Basque researchers turn light upside down February 23rd, 2018

Histology in 3-D: New staining method enables Nano-CT imaging of tissue samples February 22nd, 2018

Developing reliable quantum computers February 22nd, 2018

Imaging individual flexible DNA 'building blocks' in 3-D: Berkeley Lab researchers generate first images of 129 DNA structures February 22nd, 2018

Announcements

Basque researchers turn light upside down February 23rd, 2018

Stiffness matters February 23rd, 2018

Histology in 3-D: New staining method enables Nano-CT imaging of tissue samples February 22nd, 2018

Developing reliable quantum computers February 22nd, 2018

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

Basque researchers turn light upside down February 23rd, 2018

Stiffness matters February 23rd, 2018

Histology in 3-D: New staining method enables Nano-CT imaging of tissue samples February 22nd, 2018

Developing reliable quantum computers February 22nd, 2018

Photonics/Optics/Lasers

Basque researchers turn light upside down February 23rd, 2018

Photonic chip guides single photons, even when there are bends in the road February 16th, 2018

Rutgers-Led Innovation Could Spur Faster, Cheaper, Nano-Based Manufacturing: Scalable and cost-effective manufacturing of thin film devices February 14th, 2018

Understanding brain functions using upconversion nanoparticles: Researchers can now send light deep into the brain to study neural activities February 14th, 2018

Quantum nanoscience

Quantum cocktail provides insights on memory control: Experiments based on atoms in a shaken artificial crystal offer insight that might help in the development of future data-storage devices January 26th, 2018

Moving nanoparticles using light and magnetic fields January 25th, 2018

Scientists reveal the fundamental limitation in the key material for solid-state lighting January 25th, 2018

New oxide and semiconductor combination builds new device potential: Researchers integrated oxide two-dimensional electron gases with gallium arsenide and paved the way toward new opto-electrical devices January 10th, 2018

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



  Premium Products
NanoNews-Custom
Only the news you want to read!
 Learn More
NanoStrategies
Full-service, expert consulting
 Learn More











ASP
Nanotechnology Now Featured Books




NNN

The Hunger Project