Leonard Kelley holds a bachelor's in physics with a minor in mathematics. He loves the academic world and strives to constantly explore it.
What Is Quantum Entanglement?
Entanglement has to be one of my top science topics that sounds too fantastical to be real. Yet countless experiments have verified its ability to correlate particle properties over vast distances and cause a collapse of a value via “spooky action at a distance,” which from our vantage point seems nearly instantaneous. With that being said, I was interested in some experiments of entanglement I hadn’t heard of before and new findings involving them. Here are but a few that I found, so let’s take a closer look at the amazing world of entanglement.
Triple Entanglement and Quantum Encryption
The future of quantum computers will rely on our ability to successfully encrypt our data. Just how to do this effectively is still being investigated, but a possible route may be via a surprising triple entanglement process of three photons. Scientists from the University of Vienna and the Universitat Autonoma de Barcelona were able to develop an “asymmetric” method that was previously only theoretical. They managed this by exploiting out 3-D space.
Normally, the direction of our photon’s polarization is what allows two photons to be entangled, with the measuring of one’s direction causing the other to collapse to the other. But by altering the path of one of those photons with a third, we can incorporate a 3-D twist into the system, causing a causal chain of entanglement. This would mean one would require the twist and direction, enabling an extra layer of security. This method ensures that without the required entangled data packet, your data stream would be destroyed instead of intercepted, ensuring a secure connection (Richter).
Quantum Control and EPR Steering
Via entanglement and state collapsing, a little sneaky feature is hidden. If two people had entangled photons and one person measured their polarization, then the other persons would collapse in a way that the first person knows because of their measurement. In fact, one could use this to beat someone to measuring the state of their system and remove their ability to do anything. Causality is final, and by doing it first, I can steer the results of the system.
This is EPR steering, with the EPR referring to Einstein, Podolsky, and Rosen, who first dreamt up the spooky-action-at-a-distance experiment in the 1930s. A catch to this is how “pure” our entanglement is. If anything else were to impact a photon prior to our action of measuring it then our ability to control the order is lost, so ensuring tight conditions is key (Lee).
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When we desire to learn more about our environment, we need sensors to collect data. However, there is a limit to the sensitivity of these instruments in the field of interferometry. Known as the standard quantum limit, this prevents classically based laser light from achieving sensitivities that quantum physics predicts can be broken.
This is possible according to work by scientists from the University of Stuttgart. They utilized “a single semiconductor quantum dot” which was able to generate single photons that entered the system entangled upon hitting a beam splitter, one of the central components of the interferometer. This gives the photons a phase change which surpasses the known classical limit because of the quantum source of the photons as well as the superior entanglement they achieve (Mayer).
Entangled Clouds at a Distance
One of the central goals of quantum computing is achieving entanglement between groups of materials at a distance, but a large number of difficulties inhibit this, including purity, thermal effects, and so on. But a huge step in the right direction was achieved when scientists from the Quantum Information Theory and Quantum Meteorology at the UPV/EHU’s Faculty of Science and Technology got two different clouds of Bose-Einstein Condensates to be entangled.
This material is cold, very close to absolute zero, and achieves a singular wave function as it acts as one material. Once you split the cloud into two separate entities, they enter an entangled state at a distance. While the material is too cold for practical purposes, it is nonetheless a step in the right direction (Sotillo).
Generating Entanglement — Quickly
One of the largest hurdles to generating a quantum network is the rapid loss of an entangled system, preventing an efficiently operating network. So when scientists from QuTech in Delft announced the generation of entangled states faster than the loss of entanglement, this got people’s attention. They were able to accomplish this over a distance of two meters and, more importantly, on command. They can make the states whenever they want to, so now the next goal is to establish this feat for several stages instead of just a two-way (Hansen).
More advancements are surely on the way, so pop by every once and a while to check out the new frontiers that entanglement is establishing — and breaking.
- Hansen, Ronald. “Delft scientists make first ‘on demand’ entanglement link.” Innovations-report.com. Innovations Report, 14 Jun. 2018. Web. 29 Apr. 2019.
- Lee, Chris. “Entanglement allows one party to control measurement results.” Arstechnica.com. Conde Nast, 16 Sept. 2018. Web. 26 Apr. 2019.
- Mayer-Grenu, Andrea. “Supersensitive through quantum entanglement.” Innovations-report.com. Innovations Report, 28 Jun. 2017. Web. 29 Apr. 2019.
- Richter, Viviane. “Triple entanglement paves way for quantum encryption.” Cosmosmagazine.com. Cosmos. Web. 26 Apr. 2019.
- Sotillo, Matxalen. “A quantum entanglement between two physically separated ultra-cold atomic clouds.” Innovations-report.com. Innovations Report, 17 May 2018. Web. 29 Apr. 2019.
© 2020 Leonard Kelley