Quantum physicists achieve entanglement record

April 16, 2018, University of Innsbruck
Conceptual picture of the new exotic quantum states that have been generated in Innsbruck. The generation of quantum entanglement in a string of 20 single atoms is shown. Entanglement between neighboring atom pairs (blue), atom triplets (pink), atom quadruplets (red) and quintuplets (yellow) was observed, before the system became too complex to characterize with existing techniques. Credit: IQOQI Innsbruck/Harald Ritsch

Entanglement is of central importance for the new quantum technologies of the 21st century. A German-Austrian research team is now presenting the largest entangled quantum register of individually controllable systems to date, consisting of a total of 20 quantum bits. The physicists in Innsbruck, Vienna and Ulm are pushing experimental and theoretical methods to the limits of what is currently possible.

Some of the new quantum technologies ranging from extremely precise sensors to universal quantum computers require a large number of in order to exploit the advantages of quantum physics. Physicists all over the world are therefore working on implementing entangled systems with more quantum bits. The record is currently held by Rainer Blatt's research group at the Institute of Experimental Physics at the University of Innsbruck. In 2011, the physicists entangled 14 individually addressable quantum bits for the first time and thus realized the largest completely entangled quantum register. Now, a research team led by Ben Lanyon and Rainer Blatt at the Institute of Quantum Optics and Quantum Information (IQOQI) of the Austrian Academy of Sciences, together with theorists from the University of Ulm and the Institute of Quantum Optics and Quantum Information in Vienna, has achieved controlled multi-particle entanglement in a system of 20 quantum bits. The researchers were able to detect genuine multi-particle entanglement between all neighbouring groups of three, four and five quantum bits.

Genuine multi-particle entanglement

Physically, entangled particles cannot be described as individual particles with defined states, but only as a complete system. It is particularly difficult to understand entanglement when numerous particles are involved. Here, a distinction must be made between the entanglement of individual particles and genuine multi-particle entanglement. This can only be understood as a property of the overall system of all particles concerned, and cannot be explained by a combination of the subsystems being entangled.

At the Institute of Quantum Optics and Quantum Information in Innsbruck, the team of physicists used laser light to entangle 20 calcium atoms in an ion trap experiment and observed the dynamic propagation of multi-particle entanglement in this system. "The particles are first entangled in pairs," describes Lanyon. "With the methods developed by our colleagues in Vienna and Ulm, we can then prove the further spread of the entanglement to all neighbouring particle triplets, most quadruplets and a few quintuplets.

These detection methods were developed by Martin Plenio's research group at the University of Ulm and Marcus Huber's team at IQOQI Vienna. "We have chosen a MacGyver approach," says first author Nicolai Friis. "We had to find a way to detect multi-particle entanglement with a small number of feasible measurement settings."

The researchers took a complementary approach: The group around Huber and Friis used a method that only requires a few measurements and whose results can be easily evaluated. In this way, the entanglement of three particles could be demonstrated in the experiment. The theorists from Ulm used a more complex technique based on numerical methods. "Although this technique is efficient, it also reaches its limits because of the sharp increase in computing effort due to the number of quantum bits," says Oliver Marty from Martin Plenio's research group. "That's why the usefulness of this method also came to an end with the detection of real five-particle entanglement."

A big step towards application

"There are quantum systems such as ultra-cold gases in which entanglement between a large number of particles has been detected," says Nicolai Friis. "However, the Innsbruck experiment is able to address and read out every single quantum bit individually." It is therefore suitable for practical applications such as quantum simulations or processing. Rainer Blatt and his team hope to increase the number of bits in the experiment. "Our medium-term goal is 50 ," he says. "This could help us solve problems that the best supercomputers today still fail to accomplish."

The methods developed for the ion trap experiment in Innsbruck will be used more widely, the physicists in Ulm and Vienna are convinced. "We want to push the boundaries of our methods even further," say Friis and Marty. "By exploiting symmetries and focusing on certain observables, we can further optimize these methods to detect even more extensive multi-particle .

The research was published in Physical Review X.

Explore further: 14 quantum bits: Physicists go beyond the limits of what is currently possible in quantum computation

More information: Nicolai Friis et al, Observation of Entangled States of a Fully Controlled 20-Qubit System, Physical Review X (2018). DOI: 10.1103/PhysRevX.8.021012

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xinhangshen
1.3 / 5 (3) Apr 16, 2018
Please be aware that quantum mechanics is wrong because it does not take the effects of aether as the medium of light existing everywhere in the visible part of the universe, participating in all physical processes and delivering electromagnetic forces into account. The existence of aether is the direct conclusion of the disproof of Einstein's relativity (see https://www.resea...lativity and https://www.resea...niversal ).

Therefore, the wave property in the particle-wave duality is more likely the result of the wave of aether rather than the wave of probability which is not a physical substance and can't vibrate to become waves, but the wave of aether generated by the motion of the particle always accompanies the motion of each particle.
Da Schneib
4 / 5 (4) Apr 16, 2018
Unfortunately, @xin, this isn't theory. It's an experiment. Data trumps theory, always, and this is data. Experiments showed aether is bullshit in the 19th century; it's called the Michelson-Morley experiment. Do try to keep up.
mackita
1 / 5 (1) Apr 16, 2018
If you would follow the entanglement records made so far (1, 2, 3), then you can realize that they all have something in common - which thing it could be? (a hint: 1, 2, 3...)
Da Schneib
not rated yet Apr 16, 2018
The article would be considerably more informative if the basis or bases of the entanglement were discussed. Instead we got a hand-wave at "it's really complicated."

Do better, physorg.

On edit: luckily, the paper is not paywalled. Just follow the link at the end of the article above.
xinhangshen
3 / 5 (2) Apr 17, 2018
Unfortunately, @xin, this isn't theory. It's an experiment. Data trumps theory, always, and this is data. Experiments showed aether is bullshit in the 19th century; it's called the Michelson-Morley experiment. Do try to keep up.


Don't behave so naive and ignorant please!
mackita
1 / 5 (1) Apr 17, 2018
In dense aether model the space-time looks like undulating water surface and massive objects float on it, while shielding both surface ripples (analogy of Casimir effect), both underwater waves (analogy of gravity). Each shielding violates balance of transverse and underwater waves thus making space-time more curved and as such lensing. Dark matter arises from shielding of this shielding by nearby objects, therefore it also leads into lensing - but along connection lines of collinear objects, not around them in symmetric way.
But the same effects occurs at short distances and this effect is called entanglement. This is why the entanglement records are made with collinear bodies (1, 2, 3...)
mackita
1 / 5 (1) Apr 17, 2018
@xinhangshen is right, but the aether doesn't look like sparse thin gas (which is the model which Michelson-Morley experiment really disproved before more than one century) - but like very dense superfluid foam instead: the light is spreading along it in transverse waves, which are insensitive to motion of this environment. This is also why quantum mechanics can be modeled so well with waves at the water surface - but not with waves inside the gas.

mackita
1 / 5 (1) Apr 17, 2018
The linear arrangement of particles stabilizes entanglement up to level, the whole chains of neutral particles can be observed. According to Leif Holmlid it's possible to prepare the filamentary stacks of excited hydrogen atoms, which are held together only with Casimir and dispersion forces. What's more, Holmlid speculates that these stacks could be responsible for dark matter lensing - in this sense we could say, that dark matter filaments are formed by many tiny filaments.
Da Schneib
5 / 5 (1) Apr 17, 2018
Don't behave so naive and ignorant please!
I'm not the one ignoring an experiment from the nineteenth century; you are.
xinhangshen
not rated yet Apr 18, 2018
Don't behave so naive and ignorant please!
I'm not the one ignoring an experiment from the nineteenth century; you are.

It is you who is ignorant about what I have studied such as the well-known M-M experiment.
mackita
1 / 5 (1) Apr 18, 2018
Physicist Oliver Lodge recognized at the beginning of last century first, that aether theorists trolled aether concept in similar way like the supporters of relativity - they considered the aether as a thin sparse gas filling the space. Such an aether model would just fit the superfluid dark matter concept well - but in reality it completely ignored the luminiferous aether concept of Oliver Lodge and others, because such a sparse gas would be unable to spread light waves. But once the aether becomes a medium for transverse light waves, then it cannot represent an obstacle for them i.e. to exhibit drag. The trick is, the transverse waves aren't dragged by any environment by their very definition - no matter which thinkable or unthinkable material would be formed by. So that the luminiferous aether drag cannot be detected by Michelson-Morley experiment anyway.
mackita
1 / 5 (1) Apr 18, 2018
Why the heck transverse waves should be dragged by any environment? Not to say, when this drag is observed by just the same waves? Under such a situation even the drag of longitudinal waves wouldn't be observable in this very environment. You just cannot detect wave drag by waves dragged.

Modern physicists elevated the nondetectability of aether drag into third level once they arranged Michelson-Morley experiment not within free vacuum but inside material environment like the sapphire. Under this particular arrangement even if some residual drag of aether would exist, then from the very same reason the aether would get dragged by sapphire too resulting into zero net drag. Such an experiments just illustrate complete misunderstanding of not only environment and waves concepts - but also reference frame concept.

Da Schneib
5 / 5 (1) Apr 18, 2018
It is you who is ignorant about what I have studied such as the well-known M-M experiment.
Then describe it.
szore88
1 / 5 (1) Apr 19, 2018
I can't believe you people are talking about aether.... SMH.... This site has gone DOWN HILL the last few years...
xinhangshen
not rated yet Apr 20, 2018
Aether dynamics is governed by something like non-linear partial-differential Navier-Stokes equations, not by Maxwell's equations which have involved many wrong concepts such as electric field. The so-called electric field is just to model the force exerting on a particle, but that force is not a field because it's the force exerted by a fluid aether, just like the force exerting on an airplane, which is never a field. The real waves are the solutions of the non-linear partial-differential equations, and can't be simplified as simple transverse waves.
Da Schneib
5 / 5 (1) Apr 20, 2018
So you're sure the Michelson-Morley experiment is wrong, but you can't explain how an interferometer works.

If you can't explain how something works, you don't understand it. If you don't understand something, you can't possibly have any valid reason for declaring it to be incorrect.

I knew I had you on ignore for some reason. Now I remember what it is.
xinhangshen
not rated yet Apr 20, 2018
Da Schneib, How can you make such conclusions?

Please be aware that M-M experiment only denies a rigid aether, but what I have found is a fluid aether.

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