flashgordon - Nov 10, 2017

They should announce when they've done something a classical computer can't do.

Parsec - Nov 10, 2017

Given the known algorithm for factoring a large number into its factors using a quantum computer, I am curious how big the numbers are that a 50 qbit qc would be able to handle. Anyone have any ideas?

CubicAdjunct747 - Nov 10, 2017

Given the known algorithm for factoring a large number into its factors using a quantum computer, I am curious how big the numbers are that a 50 qbit qc would be able to handle. Anyone have any ideas?


It only has 90 microseconds of stable "up time" so not very big at this time.

javjav - Nov 10, 2017

50 bit permits to check all numbers up to 2^50, not really a big number, (in terms of prime numbers ) and that is not counting reserved bits.
In a quantum computer prime numbers are obtained by sampling (measuring) the output. Stability time is not a big issue because you only need to run the algorithm one time, from that point then every time you measure the output you will get a prime number (a random one, with as many bits as dedicated for data ). Unfortunately 50 bits is not enough to get unknown primes. But it can be invaluable as a proof of concept

Da Schneib - Nov 10, 2017

@Cubic, 90 microseconds is thirty million processor cycles at current CPU speeds. It's a long time.

@javjav, that's about correct. However DWAVE has demonstrated a 2048 bit quantum annealer so it's years not decades away.

Da Schneib - Nov 10, 2017

Oh and one other point: until there is hardware most algorithms are speculative at best. We are in our infancy in terms of quantum computing algorithms. We need computer scientists who can do quantum physics and there aren't any. Most CSs I know can barely do algebra; calculus? Forget it. They wouldn't know a calculus if it jumped up and bit them on the ass.

luke_w_bradley - Nov 10, 2017

Da Schieb, I'm a late in life physics fan boi who studied CS, and what you're talking about is a true tragedy. The flip side is good devs roll their eyes at FORTRAN code physicists crank out. The tragedy is that many of the most important ideas like symmetry and entropy manifest in both domains, but it's massively under exploited in CS (and maybe physics, I can't say)

Da Schneib - Nov 10, 2017

@luke, as I say to many, I'd have to review the code. ;)

howhot3 - Nov 10, 2017

Ok. I'm going to admit I really know nothing about quantum computers. So when people talk of a qubit, I was under the impression that it was an entangled analog values not binary, So 50 cubits would be 50 analog values not 50 binary values? If it's 50 binary values, then why not simply use a random number generator?

Da Schneib - Nov 11, 2017

@howhot, it's not really about analog computing. Remember, a qubit when finally definitively read collapses either to a 1 or a 0. It can only stay in superposition while you don't look at it. Just like a quantum particle. This has profound effects during computation that are not duplicated in either digital or analog computers. The available algorithms, to make best use of this property, cannot therefore be either digital or analog.

50 qubits is 50 quantum values.

Whydening Gyre - Nov 11, 2017

@howhot, it's not really about analog computing. Remember, a qubit when finally definitively read collapses either to a 1 or a 0. It can only stay in superposition while you don't look at it. Just like a quantum particle. This has profound effects during computation that are not duplicated in either digital or analog computers. The available algorithms, to make best use of this property, cannot therefore be either digital or analog.

50 qubits is 50 quantum values.

Which we won't know until we look at them...:-)
Spooky computing at a distance...

Da Schneib - Nov 11, 2017

That's always been the point of quantum computing, @Whyde.

Found something interesting, a categorical listing of the currently known quantum algorithms: http://math.nist....tum/zoo/

rrrander - Nov 11, 2017

Why is it everything in science and engineering today needs to be immersed in liquid helium?

Da Schneib - Nov 11, 2017

Because heat makes random noise.

derphys - Nov 11, 2017

Any simple quantum microscopic system with a sufficient large number of particles (above a few 10 ) is impossible to simulate and calculate on a classical computer, simply because the number of possibilities to calculate is too huge in a life time even over the age the universe.
The microscopic quantum complexity is dramatically more than the classical complexity.of the macroscopic world.
Quantum computers are necessary to simulate and understand our real microscopic quantum world, like complex superconductors, superfluids, magnetism, quarks.
As explained by Deutsch, any useful quantum computer calculating on many parallel micro-worlds ( 10¨512 with 512 qubits ) will prove the existence of parallel universes to our universe

derphys - Nov 11, 2017


error read 2¨512 with 512 qubits, 2 not 10 or 10¨51 rouhgly !!!!
With 10 times qubits than this IBM quantum computer, it calculates as over 2 power 512 parallel classical computers to give at random one of the ending statistical possibilities.
"That's more calculations than there are atoms in the universe, by many orders of magnitude. "
https://www.flick...9089904/

Whydening Gyre - Nov 11, 2017

That's always been the point of quantum computing, @Whyde.

Found something interesting, a categorical listing of the currently known quantum algorithms: http://math.nist....tum/zoo/

That WAS interesting.
And since I had no clue as to what I was reading. it became even SPOOKIER from a distance...:-)
But - I didn't know that until I looked at it...:-)
Funny how it all comes around full circle...

ab6pn - Nov 11, 2017

WTF the photo above looks like a hummingbird feeder.

NeutronicallyRepulsive - Nov 11, 2017

Time to sell my bitcoins.

Parsec - Nov 11, 2017

Oh and one other point: until there is hardware most algorithms are speculative at best. We are in our infancy in terms of quantum computing algorithms. We need computer scientists who can do quantum physics and there aren't any. Most CSs I know can barely do algebra; calculus? Forget it. They wouldn't know a calculus if it jumped up and bit them on the ass.


What you say is beside the point. The only relevant point is that no matter what it is, any competent CS knows how to find the information necessary to get educated on anything.

Da Schneib - Nov 11, 2017

Did you have a look at those algorithms?

This don't work like that.

Whydening Gyre - Nov 12, 2017

WTF the photo above looks like a hummingbird feeder.

Looks like a windchime I make....

pulsar8472 - Nov 14, 2017

50 is a lot. Gives me some measure of hope that I may see one in this life

SwamiOnTheMountain - Nov 14, 2017

more of an inchstone than milestone, eh?

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