Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Causing Collapse

19.03.2013
Weizmann Institute researchers suggest one can affect an atom’s spin by adjusting the way it is measured

One of the most basic laws of quantum mechanics is that a system can be in more than one state – it can exist in multiple realities – at once. This phenomenon, known as the superposition principle, exists only so long as the system is not observed or measured in any way. As soon as such a system is measured, its superposition collapses into a single state. Thus, we, who are constantly observing and measuring, experience the world around us as existing in a single reality.


All spin directions (represented by the spheres) collapse on one or the opposite direction depending on the measured photon polarization

The principle of superposition was first demonstrated in 1922 by Otto Stern and Walther Gerlach, who observed the phenomenon in the spin of silver atoms. Spin is the intrinsic magnet in quantum particles, and when a particle’s spin is in superposition, it points in more than one direction at the same time. (Instead of the north and south of magnets, these are referred to as up and down.)

Dr. Roee Ozeri and research students Yinnon Glickman, Shlomi Kotler and Nitzan Akerman, of the Physics of Complex Systems Department studied how the spin of a single atom collapsed from superposition to one state when it was observed with light. They “measured” the atom by shining laser light on it. Just as our eyes observe the world by absorbing the photons – light particles – scattered in our direction by objects, the researchers observed the process of spin collapse in the atoms by measuring the scattered photons. In results that appeared recently in Science, they showed that the direction that a photon takes as it leaves the atom is the direction that the spin adopts when superposition collapses.

Next, the team measured the polarization of the emitted photon and found that the observed polarization determines the effect of measurement on the spin. This suggests that an observer can influence the collapse of superposition just by adjusting the orientation of his photon-polarization measurement apparatus.

The reason for this “action-at-a-distance” is that the spins of the measured atoms and the emitted photons were entangled. That is, even after they were separated, a measurement of one of them instantaneously affected the other.

The experiment is an important step in understanding the measurement process in quantum systems.

Dr. Roee Ozeri’s research is supported by the Crown Photonics Center; David Dickstein, France; Martin Kushner Schnur, Mexico; the Wolfson Family Charitable Trust; and the Yeda-Sela Center for Basic Research.

Yivsam Azgad | EurekAlert!
Further information:
http://www.weizmann.ac.il

More articles from Physics and Astronomy:

nachricht Basque researchers turn light upside down
23.02.2018 | Elhuyar Fundazioa

nachricht Attoseconds break into atomic interior
23.02.2018 | Max-Planck-Institut für Quantenoptik

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Attoseconds break into atomic interior

A newly developed laser technology has enabled physicists in the Laboratory for Attosecond Physics (jointly run by LMU Munich and the Max Planck Institute of Quantum Optics) to generate attosecond bursts of high-energy photons of unprecedented intensity. This has made it possible to observe the interaction of multiple photons in a single such pulse with electrons in the inner orbital shell of an atom.

In order to observe the ultrafast electron motion in the inner shells of atoms with short light pulses, the pulses must not only be ultrashort, but very...

Im Focus: Good vibrations feel the force

A group of researchers led by Andrea Cavalleri at the Max Planck Institute for Structure and Dynamics of Matter (MPSD) in Hamburg has demonstrated a new method enabling precise measurements of the interatomic forces that hold crystalline solids together. The paper Probing the Interatomic Potential of Solids by Strong-Field Nonlinear Phononics, published online in Nature, explains how a terahertz-frequency laser pulse can drive very large deformations of the crystal.

By measuring the highly unusual atomic trajectories under extreme electromagnetic transients, the MPSD group could reconstruct how rigid the atomic bonds are...

Im Focus: Developing reliable quantum computers

International research team makes important step on the path to solving certification problems

Quantum computers may one day solve algorithmic problems which even the biggest supercomputers today can’t manage. But how do you test a quantum computer to...

Im Focus: In best circles: First integrated circuit from self-assembled polymer

For the first time, a team of researchers at the Max-Planck Institute (MPI) for Polymer Research in Mainz, Germany, has succeeded in making an integrated circuit (IC) from just a monolayer of a semiconducting polymer via a bottom-up, self-assembly approach.

In the self-assembly process, the semiconducting polymer arranges itself into an ordered monolayer in a transistor. The transistors are binary switches used...

Im Focus: Demonstration of a single molecule piezoelectric effect

Breakthrough provides a new concept of the design of molecular motors, sensors and electricity generators at nanoscale

Researchers from the Institute of Organic Chemistry and Biochemistry of the CAS (IOCB Prague), Institute of Physics of the CAS (IP CAS) and Palacký University...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

2nd International Conference on High Temperature Shape Memory Alloys (HTSMAs)

15.02.2018 | Event News

Aachen DC Grid Summit 2018

13.02.2018 | Event News

How Global Climate Policy Can Learn from the Energy Transition

12.02.2018 | Event News

 
Latest News

Basque researchers turn light upside down

23.02.2018 | Physics and Astronomy

Finnish research group discovers a new immune system regulator

23.02.2018 | Health and Medicine

Attoseconds break into atomic interior

23.02.2018 | Physics and Astronomy

VideoLinks
Science & Research
Overview of more VideoLinks >>>