Nav: Home

An experiment seeks to make quantum physics visible to the naked eye

May 03, 2016

Predictions from quantum physics have been confirmed by countless experiments, but no one has yet detected the quantum physical effect of entanglement directly with the naked eye. This should now be possible thanks to an experiment proposed by a team around a theoretical physicist at the University of Basel. The experiment might pave the way for new applications in quantum physics.

Quantum physics is more than 100 years old, but even today is still sometimes met with wonderment. This applies, for example, to entanglement, a quantum physical phenomenon that can be observed between atoms or photons (light particles): when two of these particles are entangled, the physical state of the two particles can no longer be described independently, only the total system that both particles form together.

Despite this peculiarity, entangled photons are part of the real world, as has been proven in many experiments. And yet no one has observed entangled photons directly. This is because only single or a handful of entangled photons can be produced with the available technology, and this number is too low for the human eye to perceive these photons as light.

Entangled photons amplified 100-fold

Nicolas Sangouard, a theoretical physicist at the University of Basel, together with two quantum physicists from Delft, Netherlands, and Innsbruck, Austria, has now shown in the scientific journal Optica how it may be possible to detect entangled photons directly. The basic idea of the experiment is that an entangled photon is generated and then amplified using a special technique, without destroying the quantum physical entanglement.

In the process, about 100 entangled photons are present, which, according to current knowledge, is the precise number needed to create the impression of light in humans. But although hundreds of photons reach the retina, there are also significant losses: only about seven actually reach one of the 120 million light-detecting rods of the retina. These photons then generate the nerve impulse that triggers the perception of light in the brain.

Two entangled states

In the experiment proposed by the three quantum physicists, entanglement is created by a single photon directed at a semi-transparent mirror. Sangouard explains what happens next: "The single photon is not transmitted or reflected by the mirror; instead - quantum physics is strange - the photon is simultaneously transmitted and reflected. Behind the mirror, the photon exists in a 'transmitted' and 'reflected' state, whereby these two states are entangled with another."

A photon detector and a human observer are placed behind the mirror. In order for the observer's eye to detect the entangled photons, they are amplified 100-fold with a type of magnifying glass before they reach the eye. Technically speaking, this is achieved by a displacement in phase space using a laser. Whether the human observer and/or the detector actually detect the entangled photons is not revealed directly but rather through determination of the probabilities. For this, the experiment is repeated many times and the data obtained statistically analyzed.

Very long observation period

It is not yet certain if Sangouard's group will conduct the experiment or if other quantum physicists will implement it. The required technologies - special photon sources and special lasers - are generally available today; however, the biggest obstacle is the practical implementation of the experiment. The human eye is about a billion times slower at counting weak light pulses than modern photon detectors. "According to an initial estimate, several hundreds of thousands of runs would be necessary until we have enough data to determine if we've actually detected entangled photons. This means that the test person in our experiment would have to note at one-second intervals over the course of several hundreds of hours if they have just detected a light pulse or not."

If these obstacles were overcome, the experiment would demonstrate that the human eye is able to detect quantum entanglement directly and achieve what until now has required complicated and expensive detectors. Scientists are currently working to use the principle of entanglement to build secure digital communication links and for quantum computers. According to Sangouard, these applications could benefit from the new experiment.
-end-
The research project is supported by the Swiss National Science Foundation as part of the National Center of Competence in Research in Quantum Science and Technology (NCCR-QSIT) and the John Templeton Foundation in the US.

University of Basel

Related Quantum Physics Articles:

In atomic propellers, quantum phenomena can mimic everyday physics
In molecules there are certain groups of atoms that are able to rotate.
Testing quantum field theory in a quantum simulator
Quantum field theories are often hard to verify in experiments.
Diamonds coupled using quantum physics
Researchers at TU Wien have succeeded in coupling the specific defects in two such diamonds with one another.
Quantum physics offers insight into music expressivity
Scientists at Queen Mary University of London (QMUL) are bringing us closer to understanding the musical experience through a novel approach to analysing a common musical effect known as vibrato.
More than 100,000 people challenge Einstein in a unique worldwide quantum physics experiment
On Nov. 30, more than 100,000 people participated in the BIG Bell Test, a global experiment to test the laws of quantum physics.
Quantum physicist Carl M. Bender wins 2017 Dannie Heineman Prize for Mathematical Physics
The American Institute of Physics (AIP) and the American Physical Society (APS) announced today, on behalf of the Heineman Foundation for Research, Educational, Charitable, and Scientific Purposes, that Carl M.
USC quantum computing researchers reduce quantum information processing errors
USC Viterbi School of Engineering scientists found a new method to reduce the heating errors that have hindered quantum computing.
PPPL applies quantum theory and Einstein's special relativity to plasma physics issues
Researchers at the US Department of Energy's Princeton Plasma Physics Laboratory have developed a theory of plasma waves that can infer these properties in greater detail than in standard approaches.
Quantum satellite device tests technology for global quantum network
Researchers at the National University of Singapore and University of Strathclyde, UK, report first data from a satellite that is testing technology for a global quantum network.
An experiment seeks to make quantum physics visible to the naked eye
Predictions from quantum physics have been confirmed by countless experiments, but no one has yet detected the quantum physical effect of entanglement directly with the naked eye.

Related Quantum Physics Reading:

Best Science Podcasts 2019

We have hand picked the best science podcasts for 2019. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: TED Radio Hour

Setbacks
Failure can feel lonely and final. But can we learn from failure, even reframe it, to feel more like a temporary setback? This hour, TED speakers on changing a crushing defeat into a stepping stone. Guests include entrepreneur Leticia Gasca, psychology professor Alison Ledgerwood, astronomer Phil Plait, former professional athlete Charly Haversat, and UPS training manager Jon Bowers.
Now Playing: Science for the People

#524 The Human Network
What does a network of humans look like and how does it work? How does information spread? How do decisions and opinions spread? What gets distorted as it moves through the network and why? This week we dig into the ins and outs of human networks with Matthew Jackson, Professor of Economics at Stanford University and author of the book "The Human Network: How Your Social Position Determines Your Power, Beliefs, and Behaviours".