In the world we commonly perceive around us, it takes only a slight disturbance for a pencil standing on its tip to fall in one direction or another, but in the quantum world it is possible in principle for particles of a system to fall both left and right at the same time.
Differentiating this “and” state – the quantum entanglement of particles – from the classical “or” is an experimental challenge. Scientists have now devised a
method that enables entanglement verification for states of large atomic systems.
In their experiments, the team headed by Prof. Dr. Markus Oberthaler of Heidelberg University’s Kirchhoff Institute for Physics used a classically unstable state of an ultracold atomic gas known as a Bose-Einstein condensate. This condensate is an extreme aggregate state of a system of indistinguishable particles, most of which are in the same quantum mechanical state.
The researchers used a gas of approximately 500 atoms at a temperature of 0.00000001 Kelvin above absolute zero. After a short time a system with a high degree of quantum entanglement emerged. To be able to experimentally verify this “and” state and its unique quantum mechanical properties, the team had to create a large number of these atomic systems under the same conditions and with different settings of the lab setup.
“This process required measurements over several weeks, during which the fluctuations of the magnetic field applied had to be 10,000 times smaller than the magnetic field of the earth,” explained the study’s primary author, Helmut Strobel.
Another challenge was to correctly analyse the measurements, which required the development of new statistical concepts. The goal was to extract the metrologically relevant information from the measured data. This so-called Fisher information, named after geneticist and statistician Ronald A. Fisher, explicitly and universally quantifies the sensitive dependence of a given quantum mechanical state on the metrologically relevant parameters.
According to Markus Oberthaler, conventional methods simply do not work in an atomic Bose-Einstein condensate of this size. Furthermore, the novel method can be used for even larger systems. “We can use it to verify the suitability of any experimental quantum state for precision measurements beyond what can be done with a classical state,” continues Prof. Oberthaler. “This is a hot topic in the field of quantum metrology.”
Markus Oberthaler heads the Synthetic Quantum Systems working group at the Kirchhoff Institute for Physics. Researchers from the Quantum Science and Technology in Arcetri (QSTAR) research centre and the European Laboratory for Non-Linear Spectroscopy (LENS) also contributed to the work.
Citation: H. Strobel, W. Muessel, D. Linnemann, T. Zibold, D.B. Hume, L. Pezzè, A. Smerzi, M.K. Oberthaler: Fisher information and entanglement of non-Gaussian spin states. Science 25 July 2014: Vol. 345 no. 6195 pp. 424-427, doi: 10.1126/science.1250147
- PHYSICAL SCIENCES
- EARTH SCIENCES
- LIFE SCIENCES
- SOCIAL SCIENCES
Subscribe to the newsletter
Stay in touch with the scientific world!
Know Science And Want To Write?
- How A Former Naturopath Can Help Unravel The Trickery of Alternative Medicine
- Better Brains With Beer
- Finding All-Hadronic Top - Again
- Brexit, the EU Now Has its Puerto Rico.
- Tidal Disruption Event: Black Hole Eats Star, Beams Signal To Earth
- 9,000 Years: Origin Of Farmed Rice Gets Pushed Back
- Psychiatric Diagnoses Not Valid For African-Americans, Says Sociologist
- "That's right - and it's not the first time I make this mistake!Cheers,T...."
- "I think it;'s more groups have depress because of opression and white professionals can't account..."
- " And all that science, I don't understand - it's just my job five days a week Pretty sure that..."
- "Good news for asteroid defense (it's not new news, but I only found out about it just now), this..."
- "Okay, first, this planet X, if it exists, always remains outside of Neptune if it exists - you..."
- What Happens To A Soccer Player’s Brain After Missing A Penalty Kick
- It’s Back to Shots for Flu Prevention
- ACSH Applauds Media Awareness of the Fentanyl Crisis
- Counting Bites Examined, to Help Decrease Food Intake
- The Safe And Unsafe Nutty Treats For Your Pup
- Mr. Potato Head Needs a New Warning Label!