New Quantum Record: 14 Entangled Bits

Tx-0 writes "Quantum physicists from the University of Innsbruck have set another world record: They have achieved controlled entanglement of 14 quantum bits (qubits) and, thus, realized the largest quantum register that has ever been produced. With this experiment the scientists have not only come closer to the realization of a quantum computer but they also show surprising results for the quantum mechanical phenomenon of entanglement. By now the Innsbruck experimental physicists have succeeded in confining up to 64 particles in an ion trap. 'We are not able to entangle this high number of ions yet,' says Thomas Monz. 'However, our current findings provide us with a better understanding about the behavior of many entangled particles.' And this knowledge may soon enable them to entangle even more atoms."

Comments

"Superdecoherence"

[AdmiralXyz]

From TFA:

In addition, the physicists of the University of Innsbruck have found out that the decay rate of the atoms is not linear, as usually expected, but is proportional to the square of the number of the qubits. When several particles are entangled, the sensitivity of the system increases significantly.

This is somewhat troubling, isn't it? If the decay rate is quadratic in the number of qubits, and this turns out to be due to some fundamental physical law as opposed to limitations of the current technology, does that mean we can never have quantum computers with any significant amount of memory?

Re:"Superdecoherence"

[DWMorse]

does that mean we can never have quantum computers with any significant amount of memory?

16k ought to be enough for ANYbody.

Re:"Superdecoherence"

[greeneggs2000]

From TFA:

In addition, the physicists of the University of Innsbruck have found out that the decay rate of the atoms is not linear, as usually expected, but is proportional to the square of the number of the qubits. When several particles are entangled, the sensitivity of the system increases significantly.

This is somewhat troubling, isn't it? If the decay rate is quadratic in the number of qubits, and this turns out to be due to some fundamental physical law as opposed to limitations of the current technology, does that mean we can never have quantum computers with any significant amount of memory?

Not really. The researchers trapped and entangled 14 ions in a single ion trap. Quantum computers based on ion traps will have thousands of traps, with never more than one or two ions per trap. (Machines with hundreds of traps have been tested, ions moved between traps, etc.; see, e.g., [1]) It has been known since at least 1997 [2] that you can't have a scalable system with only a single ion trap (that would be true even were the decay rate quadratic in the number of ions per trap).

[1] Home, J. P. et al. Complete methods set for scalable ion trap quantum information
processing. Science 325, 1227–1230 (2009). arXiv:0907.1865 [quant-ph]
[2] Wineland, D.J. et al. Experimental issues in coherent quantum state manipulation
of trapped atomic ions. J. Res. Natl. Inst. Stand. Technol. 103, 259–328 (1998). arXiv:quant-ph/9710025

By the way, an arXiv link for this article is arXiv:1009.6126 [quant-ph].

Re:14 quantum bits

[VortexCortex]

Hell yeah! In a few years, I will be able to play Super Mario on a quantum computer!

Yes, but then you'll have to deal with Bowser's Peach Paradox -- The game will start with the Princess being both captured and not captured, and you'll only find out which if you complete the game and observe the ending.

"I'm sorry Mario, but our Princess exists in a super position of both being in another castle, and awaiting your return safely at home."

Only after you observe the game's ending will you discover the game's plot:
You either attempted to save the Princess from the evil clutches of King Kupa,
or it's another case of Mario going mad and destroying an innocent kingdom for no good reason.

Of course the credits will either reveal that the game's events haven't taken place yet (it was all a dream (ala Mario 2), ), or that the story has all happened before, an infinite number of times, and the princes might have just been captured again!

Talk about replayability...
Insert Qubits to Contiue.

big deal

[Quiet_Desperation]

I can get more things entangled by just leaving a couple extension cords unattended for a few days.

First command!

[mfnickster]

The first command they'll run on the quantum computer:

cat schroedinger.txt | tee alive.txt dead.txt

Re:Yeah yeah, right...

[lennier]

...cut the chit-chat...does Linux run on it yet?

Yes and no.