TWIE 76: Bizarre World of Quantum Computing

This Week in Engineering - Quantum computer with the Von Neumann architecture; universal digital quantum simulation with trapped ions; scientists reproduce quantum entanglement; first universal quantum computer unveiled; Google demonstrates quantum computing for fast image search; Lockheed Martin buys a D-Wave One for undisclosed purposes; and will quantum computing make it out of the lab?
 
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Transcript For This Video

Superposition
Quantum mechanics explains a great deal, like why hydrogen in a star emits a certain frequency of light. But it also describes some weird situations. For instance, Quantum mechanics proves itÆs possible for a particleÆs spin to be in two states simultaneously: up and down. If you measure the spin, you get an answer, up or down, but if you donÆt, then the particle acts as if it were in a combination of both the states at the same time.. This Combo trait is called "superposition". And itÆs kind of like my broken sink. Maybe IÆll fix it myself. Maybe IÆll call a plumber. I could go either way. But ask me one more time and, then FINE! IÆll call a plumber! Are you happy now?!! See, by asking, you forced me into a state, Dear.

SchroedingerÆs Cat
And that brings us to animal cruelty. Regarding superposition, Erwin Schroedinger said the same thing we all did, WTF. But more eloquently using a thought experiment. He proposed sealing a cat in a box with a mechanism that would either kill the cat with cyanide gas, or not, depending on the particleÆs state. Schroedinger said that with the box closed, the state of the particle canÆt be observed, and therefore exists in both states. Concluding that the cat simultaneously exists both alive and dead. Spooky. But wait, doesnÆt the cat measure the state of the atom, thereby forcing it into one state or the other? Well, thatÆs the point of the paradox. Either way, I say the cat is a zombie. IÆve seen what cats do to the birds on my doorstep. They eat braaaaaains...

Qubits
And that brings us to qubits, or quantum bits. In a classical computer, information is stored in bits, which are either zero or one. But in quantum computers, we use particle spin that could be simultaneously zero and one. As long as we donÆt measure the spin, the particle is in both the happy cat AND zombie cat states. With classical bits, three bits are combined sequentially to make a total of eight states. But three qubits can make all eight states at once. Now, imagine a computer with hundreds or thousands of qubits. That system is so complex, it canÆt be modeled by a classical system. Surprisingly, there is such a thing as too many zombie cats.

Applications
That never gets old. How could you use quantum computing? It may allow faster searching and comparing, by using qubits to test several possibilities in parallel. But another field is cryptography. Most encryption algorithms in use today rely on the fact that splitting a large number into its prime factors takes almost exponential time. But with a quantum computer, SchorrÆs algorithm will complete the task in polynomial time. So, with quantum computing in the wrong hands, your documents, even with strong RSA encryption, are hacakble. YouÆd think homeland security and the NSA would try to stop quantum computing, but actually, theyÆre funding the research. Probably because they want to read your encrypted documents and emails. WhereÆs my tinfoil hat?

Entanglement
If you think superposition is weird, get a load of entanglement. ItÆs possible to link two particles to the same quantum state, and make them "entangled." Then, you can separate the particles, and whatever action you perform on one of the particles instantaneously happens on the other. This means quantum information travels faster than the speed of light. Also, it canÆt be intercepted. Einstein called this "spooky action at a distance", and he didnÆt believe it would work. Whatevs. I say, if you want to give your armies on Mars the attack signal without the Klingons hearing you, give æem a set of entangled particles before they leave. Take that, radio communication, and Navajo Windtalkers!

Decoherence
One of the major problems to building a working quantum computer is called decoherence. Apparently, when you store data inside single subatomic particles, that data is really freakinÆ fragile. Any vibration, or any stray electromagnetic radiation, and your data is corrupted. We need to develop technology to reduce the likelihood of a corruption, and also what to do to detect it when it happens. I know a thing or two about decoherence: do you know how many times we filmed that last story? Seriously, Dan, "enganglement?" I think heÆs been drinking.

Current Status
So, where is quantum computing today? Canadian firm D-Wave has a device that they claim is a quantum computer, though experts remain skeptical. The D-Wave One, which comes with a refrigeration unit to cool the qubits down to an amazing twenty milli-Kelvins, has been used by Google to research a super-fast way to search images using GroverÆs algorithm, and another was sold to Lockheed Martin for undisclosed purposes. Other machines are being researched, the most promising ones using trapped ions manipulated by lasers. The research is ongoing, for both the algorithms and the hardware. And frankly, itÆs starting to feel like the Arrested Development movie -- always just a few years away.

Conclusion
This week was a little different, so tell us what you think in the comments section, or if you like the show, hit the freaking like button already. ThatÆs it for this week, now get back to work.


- Quantum computer with the Von Neumann architecture - http://physicsworld.com/cws/article/news/47071

- Universal digital quantum simulation with trapped ions - http://www.sciencemag.org/content/early/2011/08/31/science.1208001

- Scientists reproduce quantum entanglement - http://www.popsci.com/scitech/article/2009-06/quantum-entaglement

- First universal quantum computer unveiled - http://www.newscientist.com/article/dn18154-first-universal-programmable-quantum-computer-unveiled.html

- Google demonstrates quantum computing for fast image search - http://www.popsci.com/technology/article/2009-12/google-algorithm-uses-quantum-computing-sort-images-faster-ever

- Lockheed Martin buys a D-Wave One for undisclosed purposes - http://www.kurzweilai.net/lockheed-martin-buys-first-d-wave-quantum-computing-system

- Will quantum computing make it out of the lab? - http://www.networkworld.com/news/2011/092611-quantum-computing-250825.html

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