223 reputation
19
bio website strilanc.com
location New York, United States
age
visits member for 4 years, 7 months
seen 2 days ago

Professional and hobbyist software developer.

Working at Google in New York.


Jun
27
accepted What operation does a beam splitter apply?
Jun
27
comment What operation does a beam splitter apply?
So it really is an ambiguous shorthand for "some operation that mixes the states, and the details should be clear in context"? Huh.. Thanks.
Jun
26
comment What operation does a beam splitter apply?
@NorbertSchuch Take this quantum circuit simulator, and use it to emulate a beam splitter. The matrices are operations to apply to a qubit. A qubit is a two level quantum system, the matrices are 2x2, so they can be applied to that system. For example, the hadamard gate transitions and OFF qubit into an (ON+OFF)/sqrt(2) qubit.
Jun
26
comment What operation does a beam splitter apply?
@NorbertSchuch You can do CNOTs in some special cases. For example, a half-wave plate placed on the top path of an interferometer can toggle the polarization of a photon conditioned on the path.
Jun
26
comment What operation does a beam splitter apply?
@NorbertSchuch Isn't a polarizing beam splitter a beam splitter that sends horizontally polarized light one way and vertically polarized light the other? That's more like a controlled-not, because it involves two qubits (the polarization and the path).
Jun
26
awarded  Curious
Jun
26
comment What operation does a beam splitter apply?
@NorbertSchuch For example, if I am representing the position of the photon as a qubit where OFF=bottom-path and ON=top-path and I'm told to place a -1 phase shift on the top path, then whether I used an H or sqrt(X) gate will affect the resulting qubit state in a measurable way.
Jun
26
comment What operation does a beam splitter apply?
@NorbertSchuch I mean: if I want to emulate a beam splitter in a quantum computer, which gates should I use.
Jun
25
asked What operation does a beam splitter apply?
Jun
9
revised How asymptotically efficient is quantum state tomography of a flat qubit?
edited body
Jun
8
awarded  Yearling
Jun
8
revised How asymptotically efficient is quantum state tomography of a flat qubit?
added 8 characters in body
Jun
8
asked How asymptotically efficient is quantum state tomography of a flat qubit?
Mar
27
answered Quantum circuit equivalent of quantum pseudo-telepathy game
Nov
7
revised Why does the classical equivalent to a quantum computer take so many bits?
added 23 characters in body
Oct
20
awarded  Commentator
Oct
20
comment Why does the classical equivalent to a quantum computer take so many bits?
@IncnisMrsi I don't know enough about physics-style entropy to clear it up. That being said, the computer-science-style entropy (i.e. message length) of an N-qubit state does increase past N as you apply non-trivial operations. You have to add bits to describe the operations; at least until you hit w 2^N bits and it's easier to just describe the weights.
Oct
16
revised Why does the classical equivalent to a quantum computer take so many bits?
deleted 1 character in body
Oct
16
revised Why does the classical equivalent to a quantum computer take so many bits?
deleted 1 character in body
Oct
16
comment Why does the classical equivalent to a quantum computer take so many bits?
@IncnisMrsi Good point. Quantum computers have to use error correcting codes to undo noise, so the classical simulation might get away with the same scheme and just use floats (the rounding error gets fixed by the noise correction)... Regardless, polynomial overhead is a lot better than the exponential people naively expect.