Blogalog 1.0.3: qubits v. quantum gates

There are a ton of interesting thoughts in Wook's latest posting. I think we'll leave the bigger issues of quantum architecture for a later posting, though I'm looking forward to that. In the meantime I'll encourage you to Google on "quantum Turing machine" and noodle on which parts of the TM need to be quantum. For some concrete stuff on where we are with this, see the references from my Aqua recommendations page and my arithmetic page.

One bit of terminology we ought to straighten out. There are two types of qubits, "flying qubits" and static ones. Flying qubits are typically something like photons. They pass through devices that cause computation, something like data values pass through gates in a classical circuit. Many quantum computing technologies use static ones, such as quantum dots or the spin of atomic nuclei. In that case, a qubit is like a bit in a register, and the "gates" (often microwave pulses) feel more like instructions to a classical computer architect. The "program" is usually called a quantum circuit in either case.

So, rather than saying that a PDP-8 takes 10k gates for its CPU, the question is, how many bits of storage does it have? A machine that can run a program might want, say, a few kilobytes.

In most quantum computing proposals, an underlying assumption is that all qubits are equal; any qubit storage location can be manipulated in an arbitrary way. It's like they are all bits in a classical register; there is no RAM/register distinction and no "load" instruction. One of the few proposals that separates qubit storage from "action" locations is the scalable ion trap processor from the Wineland group at NIST. See http://qubit.nist.gov/ and the Kielpinski Nature paper. We in the Itoh group have been thinking about how to combine different storage technologies into a larger device, like the difference between cache and RAM. Haven't gotten very far yet.

This has already gotten long, so I'll leave simulation and the qubit flythrough for another posting.

Blogalog 1.0.2: Skin

We'll get to the latest questions on quantum computer architecture shortly. Meantime, a CG question:

What's the latest on human skin? I've heard (from you) that it's extremely tough because it's partially translucent; I assume the way it stretches, folds, and wrinkles are tough to get right, too.

What's the scoop? Is anyone making significant progress?

blogalog on QC (quantum computing) & CG (computer graphics)

Wook and I are going to do a blogalog on quantum computing and computer graphics. He asks stupid questions about the former, I ask stupid questions about the latter, maybe a person or two learns something. Sometimes they'll be low-level questions, but I hope that sometimes they will also be thought-provoking.

All right, first question:

I'm doing some graphics for my quantum computing stuff, and I need to pick the location of the camera and which direction it is pointing in. I want all of my objects to appear at reasonable sizes, and the frame to be mostly full, and nothing to be cut off. My objects (just spheres and some pipes and some floating text) are of a fixed size, but the number and location vary according to the size of the quantum algorithm I'm animating, and the specific quantum computer topology. Often they are in a line, sometimes they are in a 2D grid, later they will be in more complex arrangements.

How do I pick my camera location and pointing direction?

Aqua: Advancing Quantum Architecture

Okay, so I'm way behind on posting to the blog. I've been sticking to that 20th
century technology, the mailing list.

At any rate, this is a test to see how long it will take Google to pick up the new Aqua (Advancing Quantum Architecture) web page I've created at
http://www.tera.ics.keio.ac.jp/person/rdv/quantum/index.html.

Firefox test

Just a test to see if Firefox works with the Blogger WYSWIG editor...
Have doubts about the Firefox Japanese support, may need to download a different version...

Goodness Gracious

Goodness Gracious
(played uptempo, with a good acoustic guitar hook)

Goodness Gracious is there nothing left to say?

When the ones that get to keep looking

are the ones that look away

It's pabulum for the sleepers

in the cult of brighter days

Goodness Gracious at the mercy of the crooks

We're broke and stroking vegetables

and there's way too many cooks

In every pot a pink slip, in every mouth a hook

Goodness Gracious I'm not listening anymore

Cause the spooks are in the White House

and they've justified a war

So wake me when they notify

we're gonna fight some more



Goodness Gracious not many people care

Concern is getting scarcer

true compassion really rare

I can see it in our faces, I can feel it in the air

Goodness Gracious me.



Goodness Gracious my generation's lost

They burned down all our bridges

before we had a chance to cross

Is it the winter of our discontent or just an early frost?

Goodness Gracious of apathy I sing

The baby boomers had it all and wasted everything

Now recess is almost over

and they won't get off the swing



Goodness Gracious we came in at the end

No sex that isn't dangerous, no money left to spend

We're the cleanup crew for parties

we were too young to attend

Goodness Gracious me.



Goodness Gracious my grandma used to say

The world's a scary place,

things were different in her day

What horrors will be commonplace

when my hair starts to gray?

--

Kevin Gilbert

from the album "Thud", 1994

I think this song was written a couple of years prior, during the Bush
I years. Big deficits, AIDS, the first Iraq War, the spook in the
White House.

But, I was struck by how relevant the lyrics seem today.

Kevin Gilbert was part of Toy Matinee, my own personal favorite One
Album Wonder. How many bands write songs for Salvador Dali and Vaclav
Havel? The solo album was recorded in his apartment in Pasadena.
Shortly thereafter, he died; I'm not sure how. Earlier he was part of
a band called Giraffe.

Within minutes of me sending out email, Myles had a link for me, and
there's now a Giraffe CD wending its way to Tokyo...

http://popplusone.com/

welcome

People have been telling me for a while that I should be blogging, rather than just sending out tons of email. So...