Science > Physics > Nobel Prize physicist says quantum computers will never work reliably
| Topic: |
Science > Physics |
| User: |
"Jack Sarfatti" |
| Date: |
26 Jan 2006 06:03:36 PM |
| Object: |
Nobel Prize physicist says quantum computers will never work reliably |
Nobel Prize Stanford Physicist Robert Laughlin compares R&D in quantum
computing with buying the Brooklyn Bridge. More details on why soon.
Basically reading the final answer generates too many errors for
reliable operation is I think what Laughlin is claiming. Many call
Laughlin the "new Feynman." His book is excellent - explains PW
Anderson's "More is different" general theory of emergence beyond
reductionism with lots of good practical examples in solid state physics
(crystals, metals, integer & fractional quantum Hall effects ...).
Laughlin gives powerful general reasons for why Lenny Susskind's
emergent cosmic landscape with the Weak Anthropic Principle is correct.
All physical laws are emergent collective rules. You cannot do a quantum
measurement without a spontaneous broken ground state symmetry of huge
numbers of on-mass-shell quanta. Laughlin's discussion of how Schrieffer
discovered the pair wave function (essentially breaking the number
superselection rule of Wigner) is the precursor to the current debate on
the 10^500 vacua of string theory. There was a very similar debate back
in 1957 because of the degeneracy of the "Ground State Landscape" -
though they did not call it that back then nor did they know Goldstone's
theorem the way we do today.
On Jan 25, 2006, at 6:19 PM, Jack Sarfatti wrote:
p. 38
Laughlin is explaining "More is different" with the example of
crystalline space-order rather than momentum ordering in superfluid
helium. But the idea is the same of local randomness coexisting with
nonlocal entanglement as the "organizing principle" (read local but
coherent macro-quantum order parameter).
See also p. 37 his analogy of kids in a playground!
More anon.
The problem in superfluid is that the condensate density is a small
fraction of the total fluid density at absolute zero where the total
superfluid density is 100% of the density.
Therefore, at 0 deg K
superfluid density = condensate density + ground state zero point
fluctuations
condensate density ~ |order parameter|^2 is smooth locally coherent
ground state zero point fluctuations is locally random but nonlocally
coherent.
This is same as an EPR Bell pair state where the local single-quantum
density matrix is random, but there is nonlocal coherence, e.g.
correlation of local fluctuations is phase locked as in EPR
interferometry - no local fringes, but in correlation analysis one sees
nice sharp conditional probability fringes.
At finite temperature it is a 3-fluid theory
Total Density = Superfluid Density + Normal Fluid Density
Normal Fluid as random entropic excited on-mass-shell states above the
ground state.
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| User: "Proginoskes" |
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| Title: Re: Nobel Prize physicist says quantum computers will never work reliably |
26 Jan 2006 07:47:51 PM |
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Jack Sarfatti wrote:
Nobel Prize Stanford Physicist Robert Laughlin compares R&D in quantum
computing with buying the Brooklyn Bridge. More details on why soon.
Basically reading the final answer generates too many errors for
reliable operation is I think what Laughlin is claiming. [...]
I believe the term for the unreliability is "quantum decoherence" ---
when I took a course in Quantum Computing (the physics behind it) the
professor provided several possible ways to implement a Quantum
Computer, and at least one was unstable. That was in the late 1900s,
which in the technological fields is really more like a couple decades
ago, so things may have improved, and maybe not.
--- Christopher Heckman
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| User: "" |
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| Title: Re: Nobel Prize physicist says quantum computers will never work reliably |
26 Jan 2006 07:56:25 PM |
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Quantum computers are not needed . With just the computing power we
have now and 6E9 wonderful, beautiful people walking the planet all
networked (well, many of them anyway, "all" is farther down the line) a
Global Brain automatically, cybernetically locks-in, which has
sextillions of times the power of any mind or computer now extant, so
inventing a quantum computer would just be gilding the lily, which if
you really want to do that you have to reinforce the stem. Amen.
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| User: "Bob the Builder" |
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| Title: Re: Nobel Prize physicist says quantum computers will never work reliably |
26 Jan 2006 09:36:48 PM |
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<donstockbauer@hotmail.com> wrote in message
news:1138326985.157799.25990@g14g2000cwa.googlegroups.com...
Quantum computers are not needed . With just the computing power we
have now and 6E9 wonderful, beautiful people walking the planet all
networked (well, many of them anyway, "all" is farther down the line) a
Global Brain automatically, cybernetically locks-in, which has
sextillions of times the power of any mind or computer now extant, so
inventing a quantum computer would just be gilding the lily, which if
you really want to do that you have to reinforce the stem. Amen.
Err no - we can never have computers fast enough. Especially for real-time
engineering calculations,control-systems,signal processing etc. For your
average Jo doing word processing a 486 will do fine.
Tam
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| User: "Proginoskes" |
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| Title: Re: Nobel Prize physicist says quantum computers will never work reliably |
27 Jan 2006 01:15:47 AM |
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Bob the Builder wrote:
<donstockbauer@hotmail.com> wrote in message
news:1138326985.157799.25990@g14g2000cwa.googlegroups.com...
Quantum computers are not needed . With just the computing power we
have now and 6E9 wonderful, beautiful people walking the planet all
networked (well, many of them anyway, "all" is farther down the line) a
Global Brain automatically, cybernetically locks-in, which has
sextillions of times the power of any mind or computer now extant, so
inventing a quantum computer would just be gilding the lily, which if
you really want to do that you have to reinforce the stem. Amen.
Err no - we can never have computers fast enough. Especially for real-time
engineering calculations,control-systems,signal processing etc. For your
average Jo doing word processing a 486 will do fine.
Quantum computers can do some things that traditional computers don't,
like factor in polynomial (linear?) time. Similarly, they can also
solve NP problems (Traveling Salesman, graph coloring, etc) in
polynomial time, and since there are problems that require even larger
time complexity, the time to solve these problems can be cut down
considerably.
For instance, problems based on Go and Chess are in a class called
PSPACE, so a quantum computer may be able to determine whether Chess is
a win for white, a win for black, or if the game can be drawn.
--- Christopher Heckman
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| User: "Ben Rudiak-Gould" |
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| Title: Re: Nobel Prize physicist says quantum computers will never workreliably |
27 Jan 2006 08:54:08 AM |
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Proginoskes wrote:
Quantum computers can do some things that traditional computers don't,
like factor in polynomial (linear?) time.
Cubic time. But factoring large numbers doesn't have any practical
application. It can be used to break RSA, but (a) the average user doesn't
need to break RSA, and (b) people only use RSA currently because factoring
is currently intractable. I'm not aware of any quantum algorithm that would
be useful to the average user. I guess Grover's algorithm almost qualifies.
Similarly, they can also
solve NP problems (Traveling Salesman, graph coloring, etc) in
polynomial time,
I assume you mean NP-complete. This is not true. No algorithm is known for
solving any NP-complete problem in polynomial time on a quantum computer.
The discovery of such an algorithm would render mathematicians obsolete,
since it would mean that quantum computers could prove theorems as easily as
classical computers can check them. A computer could find the shortest proof
of Fermat's last theorem, or the simplest physical theory consistent with
the empirical data, in polynomial time. Appreciating great art would be
polynomially equivalent to creating it, though we don't have an algorithmic
formulation of either of those processes at the moment.
-- Ben
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| User: "" |
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| Title: Re: Nobel Prize physicist says quantum computers will never work reliably |
29 Jan 2006 04:01:50 PM |
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Ben Rudiak-Gould wrote:
I assume you mean NP-complete. This is not true.
Wrong assumption: Non-Polynomial-Complexity (NP-time or NP-space which
is invariants). The quantum computing may provide exponential number of
"Turing computations" for a polynomial time. However the means to
express quantum computing algorithms look very restrictive to solve
such tasks (for example) as chess or any NP-hard discreet optimization
tasks.
Regards,
George
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| User: "Proginoskes" |
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| Title: Re: Nobel Prize physicist says quantum computers will never work reliably |
29 Jan 2006 07:32:47 PM |
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wrote:
Ben Rudiak-Gould wrote:
I assume you mean NP-complete. This is not true.
Wrong assumption: Non-Polynomial-Complexity (NP-time or NP-space which
is invariants).
No, NP means Nondeterministic-Polynomial (Time). Basically, a
nondeterministic machine is one that will "guess right" if there is a
correct choice among the options available.
Let's look at the TSP (an NP-complete problem): The input is a graph
with V vertices (cities), costs on the edges, and a number k. The
output is the value of the statement "There is a TSP tour with cost <=
k."
The algorithm (which runs in polynomial time) is:
(1) Choose numbers n(1), n(2), ..., n(V)
(2) Verify that the n's are all distinct; if they're not, return FALSE
(3) Verify that going from n(1) to n(2) to ... to n(V) to n(1) is one
big loop. If not,
return FALSE.
(4) Calculate the cost C from going from n(1) to n(2), plus the cost
for going
from n(2) to n(3), plus ..., all the way to n(V), and then back to
n(1).
(5) If C <= k, return TRUE; otherwise, return FALSE.
(2)-(5) of this can be done in polynomial time. The nondeterministic
machine will choose a tour whose cost is <= k, if one exists;
otherwise, an arbitrary ordering will be returned.
Any NP problem can be solved by replacing (1) with "search over all
possibilities", which will require an exponential slowdown.
The quantum computing may provide exponential number of
"Turing computations" for a polynomial time. However the means to
express quantum computing algorithms look very restrictive to solve
such tasks (for example) as chess or any NP-hard discreet optimization
tasks.
(The generalization of) chess isn't NP-hard; it's PSPACE-hard. If X is
a problem whose input has size |X|, then the answer to X can be
determined using at most C*|x|^k bits of memory, where C and k are
suitable constants. PSPACE contains NP, of course. (You only need this
much room to "run over all possibilities".)
--- Christopher Heckman
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| User: "Proginoskes" |
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| Title: Re: Nobel Prize physicist says quantum computers will never work reliably |
27 Jan 2006 11:15:23 PM |
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Ben Rudiak-Gould wrote:
Proginoskes wrote:
Quantum computers can do some things that traditional computers don't,
like factor in polynomial (linear?) time.
Cubic time. But factoring large numbers doesn't have any practical
application. It can be used to break RSA, but (a) the average user doesn't
need to break RSA, and (b) people only use RSA currently because factoring
is currently intractable. I'm not aware of any quantum algorithm that would
be useful to the average user. I guess Grover's algorithm almost qualifies.
I wasn't aware that we were talking about peons^H^H^H^H^Haverage users.
I thought we were talking about using computers in general.
Similarly, they can also
solve NP problems (Traveling Salesman, graph coloring, etc) in
polynomial time,
I assume you mean NP-complete.
If you can solve all NP-complete problems, you can solve all NP
problems. For instance, the decision problem for factoring is known to
be in NP but not NP-complete (unless someone has done something in the
past few years).
This is not true. No algorithm is known for
solving any NP-complete problem in polynomial time on a quantum computer.
I thought I had heard this somewhere. Evidently not.
--- Christopher Heckman
The discovery of such an algorithm would render mathematicians obsolete,
since it would mean that quantum computers could prove theorems as easily as
classical computers can check them. A computer could find the shortest proof
of Fermat's last theorem, or the simplest physical theory consistent with
the empirical data, in polynomial time. Appreciating great art would be
polynomially equivalent to creating it, though we don't have an algorithmic
formulation of either of those processes at the moment.
-- Ben
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| User: "David R Tribble" |
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| Title: Re: Nobel Prize physicist says quantum computers will never work reliably |
27 Jan 2006 09:35:56 AM |
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Proginoskes wrote:
Quantum computers can do some things that traditional computers don't,
like factor in polynomial (linear?) time.
Ben Rudiak-Gould wrote:
Cubic time. But factoring large numbers doesn't have any practical
application. It can be used to break RSA, but (a) the average user doesn't
need to break RSA, and (b) people only use RSA currently because factoring
is currently intractable. I'm not aware of any quantum algorithm that would
be useful to the average user. I guess Grover's algorithm almost qualifies.
You use RSA encryption every time you use your ATM card, or log in to
a secure (https, SSL) web site to do credit card transactions. So
yeah, the average user does have a stake in factoring, at least
indirectly.
Reliable and affordable quantum computers would render RSA insecure,
and any other exponential-based public-key cryptosystem, thus affecting
most digital business transactions done today.
On the other hand, while quantum computing (QC) takes away, it may
also give in return. Newer and better quantum cryptography techniques
will (probably) be invented which will be secure from even QC.
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| User: "Ben Rudiak-Gould" |
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| Title: Re: Nobel Prize physicist says quantum computers will never workreliably |
27 Jan 2006 12:11:26 PM |
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David R Tribble wrote:
You use RSA encryption every time you use your ATM card, or log in to
a secure (https, SSL) web site to do credit card transactions. So
yeah, the average user does have a stake in factoring, at least
indirectly.
My point was that there's currently no killer app that would make Joe User
buy a quantum computer when (if) they show up on the market, except maybe
Grover's algorithm. And cryptosystems naturally get phased out as the
technology for breaking them improves, so eventually fast factoring won't
even be useful to the NSA. There's only a short historical window in which
it's useful (as opposed to merely cool).
On the other hand, while quantum computing (QC) takes away, it may
also give in return. Newer and better quantum cryptography techniques
will (probably) be invented which will be secure from even QC.
Maybe. I wouldn't say probably. What's currently called "quantum
cryptography" can only secure physical wires (not virtual private networks),
so it's really no substitute for public-key cryptography, unfortunately.
-- Ben
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| User: "" |
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| Title: Re: Nobel Prize physicist says quantum computers will never work reliably |
26 Jan 2006 08:51:01 PM |
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Yu wanna flirt?:) Kan do but;
Anyhow, got a puzzle, can Yu help out here?
When a mathematician or physicist calculates time and space
do they add an equasion that takes into account that their
calculations are done on a two dimensional surface? (Or is
this just a silly question?) The reason I ask is because
artists can create the illusion of additional space by painting
a mural or a paint a trompe l'oeil,and these seem to work
best if certain natural observations are applied. Simply put
if geometry is the representation or projection of three
dimensional shapes on a two dimensional surface, do physicists
& biologists, mathematicians etc meet any similar problems in
trying to 'describe' three dimensions on a flat surface?
I came across a puzzle. I was drawing a ladder that had
fallen through a window, the window was at an oblique angle
and the top of the ladder projected into the house. To look
at the window X and Y axis were on the face of the building
(a flat plane) while the ladder fell through the window on
the Z axis(of the flat plane). With shadow and fall of light
and usual persective I corrected a turn of mind which gave
me the impression that I was working in 4 dimensions !!.
If a three dimensional object is 'projected' in two
dimensions we draw it 'monocularly', this is to say, through one
aperture, like the lense of a camera or through one eye.
Is there an addition of another dimension to accommodate
the 'present' space time ?.
(Perspective drawing varied according to cultures and through
history, we are used to seeing drawings using central convergence
point perspective. (1600's)). The addition of 'time & movement'
where a geometric drawing can be rotated say on a PC screen in order
to see the other side of the object gives the mind/brain the
illusion that we perceive three dimensions. How important is
time and movement when working in physics and mathes ?. I imagine
that there is a certain number of pictures per second above which
the mind cannot descriminate between actual movement and still
images.
N.
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| User: "Shmuel Seymour J. Metz" |
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| Title: Re: Nobel Prize physicist says quantum computers will never work reliably |
27 Jan 2006 06:13:59 AM |
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In <1138330261.711649.326150@g44g2000cwa.googlegroups.com>, on
01/26/2006
at 06:51 PM, said:
Simply put if geometry is the representation or projection of three
dimensional shapes on a two dimensional surface,
It isn't. Perhaps you're thinking of Descroptive Geometry.
--
Shmuel (Seymour J.) Metz, SysProg and JOAT <http://patriot.net/~shmuel>
Unsolicited bulk E-mail subject to legal action. I reserve the
right to publicly post or ridicule any abusive E-mail. Reply to
domain Patriot dot net user shmuel+news to contact me. Do not
reply to
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| User: "Wally Anglesea™" |
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| Title: Re: Nobel Prize physicist says quantum computers will never work reliably |
28 Jan 2006 12:57:05 AM |
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On Fri, 27 Jan 2006 00:03:36 GMT, Jack Sarfatti <sarfatti@pacbell.net>
wrote:
Well, if the only OS for it comes from Microsoft, he's probably
right....
<SNIP>
--
Find out about Australia's most dangerous Doomsday Cult:
http://users.bigpond.net.au/wanglese/pebble.htm
"You can't fool me, it's turtles all the way down."
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| User: "" |
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| Title: Re: Nobel Prize physicist says quantum computers will never work reliably |
28 Jan 2006 06:43:11 AM |
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In article <ib5mt15mkjlacf1lj80jilt0vupc9parcs@4ax.com>,
Wally Anglesea™ <wanglese@spammersbigpondareparasites.net.au> wrote:
On Fri, 27 Jan 2006 00:03:36 GMT, Jack Sarfatti <sarfatti@pacbell.net>
wrote:
Well, if the only OS for it comes from Microsoft, he's probably
right....
Microsoft doesn't know how to develop its own.
Nobody will know if, nor how useful, quantum circuitry will
be until bit gods start to play with it. IIRC, there has
only been one thingie made. This is not a computer which
is a huge collection of thingies. If there ever is one,
it will problably be a device rather than a central processor.
The biz is just rediscovering what we shipped in 1980. There's a
lot of software work that has to get done before any quantum
computing can be used. The biz hasn't even started to hone
the rough edges off comm. Time will tell if the sudden
leap into wireless was a good thing or another hindrance.
/BAH
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| User: "Andy Spragg" |
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| Title: Re: Nobel Prize physicist says quantum computers will never work reliably |
26 Jan 2006 06:28:30 PM |
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On Fri, 27 Jan 2006 00:03:36 GMT, Jack Sarfatti wrote:
(snip)
"If an elderly but distinguished scientist says that something is possible,
he is almost certainly right; but if he says that it is impossible, he is
very probably wrong." - Arthur C Clarke
How old is the distinguished scientist in question?
(follow-ups set)
Andy
--
spargeatbtinternetdotcom
No man is an island,
and almost no man is a peninsula
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