Slashdot Mirror

← Back to Stories (view on slashdot.org)

Experts Hail Quantum Computer Memory Stability Breakthrough

Posted by Soulskill on from the long-enough-to-play-some-quake-3 dept.

cold fjord writes "The BBC reports, 'A fragile quantum memory state has been held stable at room temperature for a "world record" 39 minutes — overcoming a key barrier to ultrafast computers. 'Qubits' of information encoded in a silicon system persisted for almost 100 times longer than ever before. ... "This opens the possibility of truly long-term storage of quantum information at room temperature," said Prof Thewalt ... unofficially, the previous best for a solid state system was 25 seconds at room temperature, or three minutes under cryogenic conditions. ... What's more, they found they could manipulate the qubits as the temperature of the system rose and fell back towards absolute zero. At cryogenic temperatures, their quantum memory system remained coherent for three hours. "Having such robust, as well as long-lived, qubits could prove very helpful for anyone trying to build a quantum computer," said co-author Stephanie Simmons of Oxford University's department of materials. ... "We've managed to identify a system that seems to have basically no noise." However she cautions there are still many hurdles to overcome before large-scale quantum computations can be performed. ... "This result represents an important step towards realizing quantum devices," said David Awschalom, professor in Spintronics and Quantum Information, at the University of Chicago. "However, a number of intriguing challenges still remain." — Abstract for the paywalled academic paper."

6 of 53 comments (clear)

  1. They will break all the encryption by Anonymous Coward · · Score: 0, Interesting

    The second they perfect this, they will be able to try all the keys at once and the right one will be solved instantly. All of our current generation of encryption relies on n-p complete algorithms and will become worthless ... the banking system and world economy will follow suit. Time to buy that potato farm in Idaho...

    1. Re:They will break all the encryption by JoshuaZ · · Score: 4, Interesting

      Er, "strongly conjectured to occur" should be "strongly conjectured to *not occur*. Need to proofread more when using preview. Also, as long as I'm replying to myself, note that the set of problems which can be solved easily by a quantum computer is BQP http://en.wikipedia.org/wiki/BQP, but it is likely that for many practical applications, one will want the set of problems where a quantum computer can quickly convince a classical computer that it really has a solution, and this set, ZBQP, is likely much much smaller https://complexityzoo.uwaterloo.ca/Complexity_Zoo:Z#zbqp. Factoring lives in this smaller set because the classical computer can check the quantum computer's work essentially by just multiplying together the factors given by the quantum machine.

    2. Re:They will break all the encryption by sd4f · · Score: 4, Interesting

      I actually went to a talk by a Prof. Michelle Simmons on this last night, and asked that question. My understanding is that it would just does all the calculations at once, in a massively parallel operation (which obviously isn't efficient). I'm no computer scientist (just a mechanical and mechatronic engineer) and I don't really know anything behind quantum mechanics, but the other thing mentioned in the talk about a quantum computer is that it would have perfect security (her words), because, and now i'm relying on memory, a quantum computer doesn't store data like a classic computer, as it can't be perfectly replicated, so the quantum computer needs to keep the qubits active for as long as possible in the computer (hence the importance of the coherence time, as stated in the article). Because a quantum computer is an adiabatic system, it sends the 'energy' from one place to another. Eavesdropping would mean you reroute that energy, and it doesn't go to its intended place.

      A lot of it went over my head, so take this with a spoon of salt, as I could have botched it up, but that's the gist of my understanding, and off-topic info

  2. And it was so simple to do... by TempeNerd · · Score: 4, Interesting

    I am just amazed at the technology that is going into making this new qubit.

    First off it is "...built with a highly purified form of silicon" and one qubit requires "... the spins of the 10 billion or so phosphorus ions..."

    Now THAT is engineering!

  3. Re:Nice, but... by cold+fjord · · Score: 4, Interesting

    I would guess 15-20, more or less, depending on the specific application. The history of the NSA's involvement with the DES encryption algorithm is instructive.

    NSA's involvement in the design (of DES)

    I would also highlight the last sentence in the section: " Bruce Schneier observed that "It took the academic community two decades to figure out that the NSA 'tweaks' actually improved the security of DES."[12] "

    --
    much of left-wing thought is a kind of playing with fire by people who don't even know that fire is hot - George Orwell
  4. Another observation by Okian+Warrior · · Score: 4, Interesting

    We are also testing the boundaries of the physical universe in a completely new realm.

    The number of states in a quantum-entangled set of particles goes exponentially with the number of particles. For 10 particles (entangled) it takes 2^10 states for the universe to represent the possible outcomes. For 1,000 entangled particles, the number of states is 2^1000.

    The number of particles in the entire universe is only about 2^80.

    Managing 1,000 entangled particles would require the universe to keep track of a staggering amount of information. Does the underlying machinery have information-space this big? No one knows.

    For the first time, we can measure the boundaries of the physical mechanism that underlies the universe in a completely different realm: information capacity. This is analogous to a program probing the limits of RAM memory by seeing how much it can allocate.

    Here's hoping that we don't find a buffer overflow.