Shining new light on quantum nonlocality effect
A team from Griffith’s Centre for Quantum Dynamics in Australia have demonstrated how to rigorously test if pairs of photons – particles of light – display Einstein’s “spooky action at a distance”, even under adverse conditions that mimic those outside the lab.
They demonstrated that the effect, also known as quantum nonlocality, can still be verified even when many of the photons are lost by absorption or scattering as they travel from source to destination through an optical fiber channel. The experimental study and techniques are published in the journal Science Advances.
Quantum nonlocality is important in the development of new global quantum information networks, which will have transmission security guaranteed by the laws of physics. These are the networks where powerful quantum computers can be linked.
Photons can be used to form a quantum link between two locations by making a pair of photons that are “entangled” – so that measuring one determines the properties of its twin – and then sending one along a communication channel.
Team leader Professor Geoff Pryde said a quantum link had to pass a demanding test that confirmed the presence of quantum nonlocality between particles at either end.
“Failing the test means an eavesdropper might be infiltrating the network,” he said.
“As the length of quantum channel grows, less and less photons successfully pass through the link, because no material is perfectly transparent and absorption and scattering take their toll.
“This is a problem for existing quantum nonlocality verification techniques with photons. Every photon lost makes it easier for the eavesdropper to break the security by mimicking entanglement.”
Developing a method to test entanglement in presence of loss has been an outstanding challenge for the scientific community for quite some time.
The team used a different approach – quantum teleportation – to overcome the problem of lost photons.
Dr Morgan Weston, first author of the study, said they selected the few photons that survived the high-loss channel and teleported those lucky photons into another clean and efficient, quantum channel.
“There, the chosen verification test, called quantum steering, could be done without any problem,” she said.
“Our scheme records an additional signal that lets us know if the light particle has made it through the transmission channel. This means that the failed distribution events can be excluded up front, allowing the communication to be implemented securely even in the presence of very high loss.”
This upgrade doesn’t come easy – the teleportation step requires additional high-quality photon pairs on its own. These extra photon pairs have to be generated and detected with extremely high efficiency, in order to compensate for the effect of the lossy transmission line.
This was possible to achieve thanks to state of art photon source and detection technology, jointly co-developed with the US National Institute of Standards and Technology in Boulder, Colorado.
Although the experiment was performed in the laboratory, it tested channels with photon absorption equivalent to about 80 km of telecommunications optical fiber.
The team aims to integrate their method into quantum networks that are being developed by the Australian Research Council Centre of Excellence for Quantum Computation and Communication Technology, and test it in real-life conditions.
The Latest on: Quantum nonlocality effect
[google_news title=”” keyword=”quantum nonlocality effect” num_posts=”10″ blurb_length=”0″ show_thumb=”left”]
- Quantum Computing Will Change the World. How to Play the Stocks.on November 24, 2022 at 10:09 pm
Last month, the Royal Swedish Academy of Sciences awarded the Nobel Prize in physics to three scientists for their research on quantum information ... to overestimate the effect of a technology ...
- Quantum city simulation shows how to make Paris-sized quantum interneton November 24, 2022 at 4:33 pm
These devices would take advantage of quantum effects to make information sharing … A 48,500-year-old virus has been revived from Siberian permafrost Promising universal flu vaccine could ...
- Quantum Particles Aren’t Spinning. So Where Does Their Spin Come From?on November 23, 2022 at 5:57 pm
They can’t spin; proving that it’s impossible for electrons to be spinning is a standard homework problem in any introductory quantum physics course. If electrons actually spun fast enough to ...
- Quantum progress: How IBM, Microsoft, Google and Intel compareon November 23, 2022 at 7:39 am
Watch now. Established enterprise leaders like IBM, Microsoft and Google continue to make progress in quantum computing. As a result, quantum computers are getting bigger and achieving ...
- This will not be on the test: A new approach to learning quantum chemistryon November 23, 2022 at 3:04 am
Quantum mechanics. Quantum tunneling, Quantum computing. Quantum biology. The implications of the quantum world are extraordinary — and potentially intimidating to students trying to maintain a good ...
- Fixing the next big tech skills shortage will need a quantum leapon November 21, 2022 at 4:00 pm
Like most tech sectors, quantum computing has a skills shortage. According to a September 2022 report by the World Economic Forum (WEF), more than half of quantum computer companies are currently ...
- Quantum algorithms save time in the calculation of electron dynamicson November 21, 2022 at 4:00 pm
Quantum computers promise significantly shorter computing times for complex problems. But there are still only a few quantum computers worldwide with a limited number of so-called qubits.
- A new experiment pushes the boundaries of our understanding of topological quantum matteron November 17, 2022 at 1:39 pm
"What our experiment accomplished—by clarifying the presence of bosons rather than fermions—is to open the door to using the thermal Hall effect in the same way that the quantum Hall Effect ...
- Quantum computing moves from the theoretical to local startupson November 17, 2022 at 1:22 pm
in a kind of snowball effect. “It’s still pretty early” for quantum computing, says Russ Wilcox, a partner at the venture capital firm Pillar. “But a number of companies are starting to ...
- Enzymes could be key to understanding how DNA mutates, quantum biologists findon November 16, 2022 at 6:38 am
This finding sheds new light on the assumed theory that suggests quantum effects would not survive long enough to be impacted by the replication process. Max Winokan, a co-author of the study from ...
via Google News and Bing News