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?

- 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 -

- Will quantum computing make it out of the lab? -

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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 it¦s possible for a particle¦s 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 don¦t, 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 it¦s kind of like my broken sink. Maybe I¦ll fix it myself. Maybe I¦ll call a plumber. I could go either way. But ask me one more time and, then FINE! I¦ll call a plumber! Are you happy now?!! See, by asking, you forced me into a state, Dear.

Schroedinger¦s 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 particle¦s state. Schroedinger said that with the box closed, the state of the particle can¦t be observed, and therefore exists in both states. Concluding that the cat simultaneously exists both alive and dead. Spooky. But wait, doesn¦t the cat measure the state of the atom, thereby forcing it into one state or the other? Well, that¦s the point of the paradox. Either way, I say the cat is a zombie. I¦ve seen what cats do to the birds on my doorstep. They eat braaaaaains...

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 don¦t 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 can¦t be modeled by a classical system. Surprisingly, there is such a thing as too many zombie cats.

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, Schorr¦s 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. You¦d think homeland security and the NSA would try to stop quantum computing, but actually, they¦re funding the research. Probably because they want to read your encrypted documents and emails. Where¦s my tinfoil hat?

If you think superposition is weird, get a load of entanglement. It¦s 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 can¦t be intercepted. Einstein called this "spooky action at a distance", and he didn¦t 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 µem a set of entangled particles before they leave. Take that, radio communication, and Navajo Windtalkers!

One of the major problems to building a working quantum computer is called d