Somebody recently tweeted the term "transmon qubit" to the Science Scout twitter account, and (for the life of me) I cannot wrap my head around what it is exactly (other than a piece of delicious sounding science jargon).
As far as I can make out, it has something to do with a bit unit in the computation sciences context, which happens to quantum properties. i.e. Not just binary, but more a binary plus this "both, at the same time" option.
Anyway, if anyone can shed some light (a la Bill Nye style) on this term then it would be greatly appreciated.
Physical Science
Comments
Glad to be of help!
A qubit is a quantum computer bit.
A quantum computer is a computer that, by superimposing multiple quantum states, can effectively cover multiple alternatives in a single step. In the extreme case, what that would mean is that if you wanted to crack the password on an encrypted file, you could throw a quantum computer at it, and it would explore all of the possible passwords at the same time; the quantum state of the qubits would collapse on the answer.
The biggest challenge in making quantum computers real is designing qubits. In a standard computer, a bit is a storage cell that's used during a computation that can store one single on/off state. Computation is a process of taking a bunch of bits from some place in storage, doing something to them, and then putting the result back into some place in storage.
For quantum computing, you want the same thing. You want to have some set of memory cells that contain a bit in an indeterminate quantum state - and you want to be able to "read" a collection of them, combine them in some way, and produce a result. The quantum state shouldn't collapse until someone tries to read it out into non-quantum bits.
Making working qubits is hard. First, things don't like to stay in an indeterminate state for long - unless you're doing something *very* clever, they tend to collapse very fast. It's particularly hard to take multiple things in indeterminate states, and combine them to get a result without collapsing the state.
There are about a dozen different proposals for ways of building a working qubit. None of them are really particularly close to being stable enough to use to build a working quantum computer. Each has is strengths, and weaknesses - but so far, none really work.
The transmon qubit is one proposal for how to build a working qubit, which was designed by a team at Yale. It's a fairly promising design, and it's got some unusual properties. In particular, something that I don't understand about its design provides a way of studying the interplay between the readout (the mechanism that collapses the qubit state and provides a concrete output state), and the quantum storage bit itself.
Posted by: Mark C. Chu-Carroll | July 6, 2009 3:43 PM
Thanks Mark,
That is so awesome at so many different levels!
Posted by: David Ng | July 7, 2009 2:11 AM
Nice, thanks for the bigs heads up!
Posted by: Mateus | July 8, 2009 12:15 AM