February 18, 2008

Quantum Construction

Posted by Arcane Gazebo at 3:19 PM


quantum construction, originally uploaded by arcanegazebo.

I spotted this sign while running in Berkeley this morning, and had to go back for a photo. From the slogan it looks like they're promoting energy-efficient home design, which is commendable; thus they probably want "quantum" to indicate "technologically advanced". But of course, "quantum" also brings to mind uncertainty, which maybe isn't what a contractor wants to associate themselves with. At the very least, I would expect Quantum Construction to be able to give a precise time estimate, or a precise cost estimate, but not both.

However, I assume their creation operators are top-notch.

May 6, 2007

Bad quantum press releases: this time, it's personal

Posted by Arcane Gazebo at 10:19 PM

Scott Aaronson points out an overly-excited press release from NEC, which claims: "NEC, JST and RIKEN successfully demonstrate world's first controllably coupled qubits". This was indeed an exciting development when we published it five months ago. At best NEC has the world's fourth controllably coupled qubits.

That said, the stupidity seems to be limited to the press release, and the paper actually looks pretty interesting, apparently with time domain results that no one else has shown. (I haven't been on the campus network today so I haven't had a chance to read more than the abstract.)

March 7, 2007

March Meeting, Days 2 and 3

Posted by Arcane Gazebo at 9:06 PM

I thought about posting last night but this was pre-empted by the fact that the slides for my talk were unfinished (and also the Clarke group dinner). First I want to register a complaint:

hund's rules for conference seating

This is how physicists (or maybe everybody) fill seating at conferences. The first people to arrive take the seats on the outside of the rows, and then fill in to the middle. This is really annoying when arriving in the middle of the session and having to climb over a bunch of people to get into the one empty seat. I am aware that this is a really lame complaint, but please, fill from the middle!

Now that I've got that out of my system: the last couple days were a blur of superconducting qubit talks. There's a lot going on in this field, and most groups had three or four (10-minute) talks in a row to have enough time to explain all their results. One experiment I thought was very neat was this one from Terry Orlando's group at MIT. In flux qubits like the ones we study, one can measure the temperature by sweeping the flux bias across the degeneracy point and measuring the population of the qubit states. Higher temperatures will give wider curves, as energies further away from the degeneracy point are more likely to be populated by thermal activation. When we measure this on our qubits we usually get something like 150 mK, mysteriously somewhat higher than the fridge temperature (roughly 50 mK).

What the Orlando group did was to apply an analog of laser cooling (as in atomic physics) to their qubit, using a microwave pulse to induce transitions that ultimately cool the system. As a result they were able to see these temperatures (as measured from the widfh of the qubit step) reduced by a factor of 100, from 300 mK to 3 mK. It was pretty impressive; I'm not sure how important it is for quantum computing or whether it's something we should be doing with our qubits, but it's a nice application of techniques from another field.

This morning I gave my talk, which was helpfully introduced by Frank Wilhelm's talk immediately prior, in which he said something like "the really important development for scalability is what Travis Hime will talk about next". So the pressure was on, but I think I did ok. After this was... more qubit talks, but I was mostly decompressing after finishing mine and didn't pay as much attention as usual.

Tomorrow I go to see talks by other Clarke group members, including John himself. And then, an evening flight back to Berkeley.

Permalink | Tags: Academia, Physics, Quantum Information, Science

March 5, 2007

March Meeting, Day 1

Posted by Arcane Gazebo at 9:50 PM

bear peering in glass

Actually I spent much of today working on my talk instead of going to sessions. The superconducting qubit sessions start tomorrow morning and basically run continuously until Thursday evening. I did go to some talks in the afternoon, though, mostly in D2: Ion Traps for Scalable Quantum Computation. (In some sense this is our competition.)

Ike Chuang, who is a big name in this field, gave the first talk, which laid out the challenges in making a practical quantum computer with ion traps. Most of this dealt with error correction; according to Shannon's theorem (or maybe a quantum information version thereof) it should be possible to build an error-free quantum computer out of qubits that do make occasional errors, as long as the failure rate is below some threshold. Unfortunately in some cases they've looked at this requires a prohibitively large number of operations, as many as 1020. One can try to implement various error-correcting codes, such as Shor's or Steane's, but certain operations that are needed for a universal quantum computer don't work within these codes. And in fact Chuang et al. have shown that there is no stabilizer code that allows a universal set of operations to be performed within the code—one has to decode first before performing at least one of the operations.

The other talks in the session were less abstract, and thus harder to understand (since I'm not terribly familiar with this architecture). The talk by Slusher described a proposal for a VLSI-based scalable ion-trap based quantum computer, which seemed impressive, except I'm pretty sure this is the one Chuang mentioned that would require 440 watts of laser power to operate.

I skipped out on the last talk to go to D8: Superconductivity: STM of Cuprates and see what the group I worked in as an undergrad was up to. However, I haven't thought about STM of cuprates for a while now and only had the faintest idea what they were talking about.

A tempting alternative for the end of the day was Session D33: Focus Session: Quantum Foundations II. It starts out as a perfectly normal session, but somewhere around 4:30 becomes the dumping ground for crackpots. For example:

D33.00014 : Do Particles have Barcodes?

If an elementary particle shown in Fig 2 of gr-qc/0507130 has an UNSTABLE quantum connection to the rest of the universe calibrated by nature in terms of Planck times, as also proposed in my separate MAR07 abstract, there exists a possibility that each particle has a barcode of its own. Instability implies varying periods of connections and disconnections of particles to the universe, which would be equivalent to the varying widths of white and black strips of commercial barcodes. Considering the high order of magnitude of Planck times in a second, each particle and the universe generated by its radiations may have their unique birth times registered in their barcodes. My quest for the cause of consciousness, in MAR06 abstracts, as an additional implication of physics/0210040, leads to the inquiry if these unique parallel universes are like the ones that give rise to consciousness as proposed by some physicists. With all due respect, the attempts to explain TOE of inert matter may not be attempts to explain one step to climb up on a stairway at a time. They may be attempts to explain only half a step at a time to on a stairway made with only integer number of steps. The search for TOE assumes such a theory exists. Mathematics has no barrels to fire bullets that can shoot down a non-existent bird. A Hamiltonian knows no consciousness, a missing ingredient of biology made of particles or vice versa, and of realistic TOE.

The talk after that one describes a theory of Atonic Physics [sic], which sounds like an outtake from Monty Python's bookstore sketch.

Permalink | Tags: Academia, Physics, Quantum Information, Science

February 27, 2007

Quantum mechanical Tomb Raider

Posted by Arcane Gazebo at 1:44 PM

Terence Tao explains quantum mechanics by analogizing to video games (particularly Tomb Raider):

Now, how does the situation look from Lara’s point of view? At the save point, Lara’s reality diverges into a superposition of two non-interacting paths, one in which she dies in the boulder puzzle, and one in which she lives. (Yes, just like that cat.) Her future becomes indeterministic. If she had consulted with an infinitely prescient oracle before reaching the save point as to whether she would survive the boulder puzzle, the only truthful answer this oracle could give is “50% yes, and 50% no”.

This simple example shows that the internal game universe can become indeterministic, even though the external one might be utterly deterministic. However, this example does not fully capture the weirdness of quantum mechanics...


He goes on to make some macabre modifications to the game mechanics in order to improve the analogy, bringing in interference and entanglement. It's an entertaining post, but it gets truly ridiculous in the comments where he devises a Tomb Raider level to test Bell's Inequality.

Permalink | Tags: Games, Physics, Quantum Information

February 12, 2007

Sixteen Qubits (starring Molly Ringwald)

Posted by Arcane Gazebo at 11:30 AM

There's been some buzz lately about D-Wave's sixteen-qubit quantum computer that they're planning to demonstrate tomorrow. Instead of writing a post on this I'm just going to link to (and endorse) Scott Aaronson's post on the subject. There's a lot of skepticism about D-Wave in the community.

Permalink | Tags: Physics, Quantum Information, Technology

November 30, 2006

Publication: Solid-State Qubits with Current-Controlled Coupling

Posted by Arcane Gazebo at 2:29 PM

As some of you know, we recently had a paper accepted to Science. The paper appears in the latest issue, and is now available online.

I will try to post something in the next few days that explains these results for the non-physicists in the audience. In the meantime, there's this post from March about these experiments (from before we had the major findings), and here's the abstract:

Solid-State Qubits with Current-Controlled Coupling

T. Hime, P. A. Reichardt, B. L. T. Plourde, T. L. Robertson, C.-E. Wu, A. V. Ustinov, John Clarke

The ability to switch the coupling between quantum bits (qubits) on and off is essential for implementing many quantum-computing algorithms. We demonstrated such control with two flux qubits coupled together through their mutual inductances and through the dc superconducting quantum interference device (SQUID) that reads out their magnetic flux states. A bias current applied to the SQUID in the zero-voltage state induced a change in the dynamic inductance, reducing the coupling energy controllably to zero and reversing its sign.

Permalink | Tags: Lab, Physics, Publications, Quantum Information, Science

June 20, 2006

Publication: Quantum theory of three-junction flux qubit with non-negligible loop inductance: Towards scalability

Posted by Arcane Gazebo at 11:37 AM

Here's the latest publication on Clarke group qubit research, which appeared in Physical Review B at the end of May. Normally I give a non-technical explanation in these posts, but this paper is entirely devoted to working out gory technical details. It essentially goes through how to calculate a priori the properties of the flux qubits that I've written about previously. This calculation had been done for "small" qubit loops—small being defined in terms of the loop inductance but corresponding to a few microns on a side—our qubits are much larger than this (100 microns) and so we needed to figure out the more general solution.

The vast majority of the work in this paper was done by T. L. Robertson; my primary contribution was checking the math and the Mathematica code.

Quantum theory of three-junction flux qubit with non-negligible loop inductance: Towards scalability

T. L. Robertson, B. L. T. Plourde, P. A. Reichardt, T. Hime, C.-E. Wu, and John Clarke
Phys. Rev. B 73, 174526 (2006)

The three-junction flux qubit (quantum bit) consists of three Josephson junctions connected in series on a superconducting loop. We present a numerical treatment of this device for the general case in which the ratio betaQ of the geometrical inductance of the loop to the kinetic inductance of the Josephson junctions is not necessarily negligible. Relatively large geometric inductances allow the flux through each qubit to be controlled independently with on-chip bias lines, an essential consideration for scalability. We derive the three-dimensional potential in terms of the macroscopic degrees of freedom, and include the possible effects of asymmetry among the junctions and of stray capacitance associated with them. To find solutions of the Hamiltonian, we use basis functions consisting of the product of two plane wave states and a harmonic oscillator eigenfunction to compute the energy levels and eigenfunctions of the qubit numerically. We present calculated energy levels for the relevant range of betaQ. As betaQ is increased beyond 0.5, the tunnel splitting between the ground and first excited states decreases rapidly, and the device becomes progressively less useful as a qubit.
Permalink | Tags: Physics, Publications, Quantum Information, Science

June 19, 2006

Quantum wiki

Posted by Arcane Gazebo at 5:44 PM

Via Mason, some guys at Caltech have set up a quantum information wiki intended for the research community. I added a page for myself, a stub page for the Clarke group, and updated their list of blogs to include this page and Mixed States. At the moment there's not much there from the solid state angle, so I may be back to contribute a bit more.

Permalink | Tags: Caltech, Internet, Physics, Quantum Information, Science

April 12, 2006

Life imitates art: superhero tryouts

Posted by Arcane Gazebo at 12:11 PM

Via Pharyngula, these tryouts for Stan Lee's new superhero reality show remind me of nothing so much as the hero recruitment drive in Mystery Men. Perhaps I could use my quantum coherence research to develop a superhero persona, but my powers would only work if no one observes them. (Maybe this is just a secret identity requirement.) However, the field is probably rife with potential supervillainy.

Permalink | Tags: Comics, Culture, Movies, Quantum Information, Television

March 29, 2006

Wednesday Schrodinger's Cat Blogging: Coupled Qubits

Posted by Arcane Gazebo at 12:45 PM

The slides for my March Meeting talk, "Variable Coupling of Two Flux Qubits", are now available online. As promised, below the fold is a non-technical explanation of the results presented there. This work builds on the single-qubit work, about which I posted in August; it may be helpful to review that post before reading the following.

Continue reading "Wednesday Schrodinger's Cat Blogging: Coupled Qubits"
Permalink | Tags: Physics, Quantum Information, Science

March 27, 2006

Scary vs. gross [Open Thread]

Posted by Arcane Gazebo at 10:20 AM

It's spring break, but I don't have any vacation plans. I do have some travel lined up later on this spring: I bought my tickets for Coachella so I'll be seeing some of you there next month.

The Hills Have Eyes: This movie was so bad I'm just going to leave V for Vendetta on the sidebar. Normally I like horror flicks, but this one seemed unclear on the concept. Specifically, the film confuses "scary" with "gross", and so we get a lot of gore and ugly mutants but not a lot of suspense. Instead of being frightening the experience was merely unpleasant, and it wasn't even the most disgusting thing I'd seen all week (David Bowie's eyeball hanging out of its socket being the clear winner there). The protagonists are dumb even by horror movie standards—Roger Ebert writes pretty much his entire review on how dumb they are—and some of them are sufficiently annoying that I was rooting for the mutants within ten minutes or so. Some critics have suggested that the movie is an allegory for the Iraq war. Such a film would have been much more interesting; in reality the movie drags out a few political stereotypes but doesn't sign on to an agenda or pursue anything as sophisticated as an allegory.

Charles Stross:Iron Sunrise: Here's the problem with "hard sci-fi": sometimes the author knows just enough physics to get it wrong. For example: this novel's faster-than-light communication scheme involving EPR-style entangled qubits. Now, I'm one of the few readers of this book who actually has a pair of entangled1 qubits in his2 basement. But any competent physicist should know that information can't be transferred this way—you just get correlated random numbers. (You can make a one-time pad this way for quantum cryptography, and indeed this has been done.)

All this shows is that I'm a big nerd. Once I stopping thinking very hard about the physics in the book, it turned into a fun pulp novel, with spies, assassins, conspiracies, and Nazi villains (or near enough). Once the plot really got going I was hooked, and it was an excellent way to pass the time while I was stuck in the airport last weekend. One non-science complaint I had was that the plot twists were all telegraphed in advance, so there weren't any big surprises. However, the characters were well-written and just reading about their interactions was fun.

1It's actually debatable whether they are entangled (I suspect they are) but they are definitely coupled. More on this in an upcoming post.
2Actually, UC Berkeley's basement.

Arab Strap: The Last Romance: I felt like I am not nearly bitter enough to appreciate this album properly. And this is supposed to be one of Arab Strap's more uplifting records! Well, the tone does get happier as the CD plays, culminating in the nearly-triumphant "There Is No Ending". (The US version of the album has two bonus tracks, but that one is clearly the end of the album.) Overall this is a decent album with a few excellent tracks: the first song and the aforementioned last song; another one I like is "Don't Ask Me To Dance". For the most part I like the darker music, which probably means I should check out their other records which are supposed to be along the same lines. (This purchase finally prompted me to find out that the Belle & Sebastian album The Boy With The Arab Strap was named after this band, and not the other way around.)

Permalink | Tags: Books, Movies, Music, Open Thread, Physics, Quantum Information

February 27, 2006

A different take on quantum cuteness [Open Thread]

Posted by Arcane Gazebo at 3:32 PM

First, a follow-up link to the quantum interrogation post: Sean at Cosmic Variance explains the experiment in layman's terms. I'm guessing he wrote this post immediately after reading Cute Overload.

Anyway, it's now time to review the album I've been playing incessantly the last three weeks. No, not Loveless, the other one.

Belle & Sebastian: The Life Pursuit: I am hardly an unbiased source on this band, so when I say that the album is awesome you will probably not be surprised. At least I can say how it stands in relation to the other B&S records, which is what I spent the first ten or so plays trying to figure out. In general it has a somewhat different sound from their previous work. There's still the sunny mood that ran through most of Dear Catastrophe Waitress (in fact the word "sun" appears in two of the song titles), but without the orchestral feel that characterized the earlier LP's production. From a production perspective, it sounds fairly novel for this band. I'm not sure how I would descibe this new sound, but it's quite appealing and a good match for the themes of the album.

It feels very cohesive compared to Waitress (in which they seemed to be experimenting with various styles on the different tracks)—these songs flow into each other very smoothly, and when "Act of the Apostle II" picks up the theme from its predecessor halfway through, it feels completely natural despite the fact that the first "Act of the Apostle" played ten tracks earlier. This is not to say that there's no variety; "Dress Up In You", which sounds like an old-school B&S song, is sandwiched between "The Blues Are Still Blue" and "Sukie In The Graveyard", both of which are far peppier than is typical for this band.

On just about every Belle & Sebastian CD I've bought, there's been one song that I've fallen in love with and played to excess. Joining "Your Cover's Blown", "If She Wants Me", "String Bean Jean", and "Like Dylan in the Movies" is "The Blues Are Still Blue" from this record. I'm not sure what it is about this particular song (maybe the cowbell) but I can't get enough of it. Other highlights are "Funny Little Frog", "Another Sunny Day", and "Sukie in the Graveyard".

The iTunes version of this album offers two bonus tracks, neither of which is particularly essential. "Meat and Potatoes" sounds as if it was written for the Dr. Demento show, and "I Took A Long Hard Look" is forgettable. (Apparently these are also on the "Funny Little Frog" single.) Anyway, this only applies if you bought the CD but were considering getting the extra tracks; spend your $0.99 on "Your Cover's Blown" (from the Books EP) instead.

Permalink | Tags: Music, Open Thread, Physics, Quantum Information, Science

February 23, 2006

Counterfactual computation

Posted by Arcane Gazebo at 5:18 PM

I've been neglecting the blog the last few days, in favor of things like data analysis. Although I might have preferred to be doing things like Half-Life 2 instead, the data came out very well, and you will certainly see it if you attend my March Meeting talk.

In other quantum computing news, a group at UIUC has performed a very interesting experiment in which they combined quantum computing and quantum interrogation to get the result of a quantum algorithm without actually running it. (Via all over the place.) So at least one person will have a March Meeting talk that's much cooler than mine—for us "counterfactual computation" is when our qubits don't work—but in the spirit of quantum oneupsmanship I will note that my qubits are (allegedly) scalable.

UPDATE: John Holbo speculates about technological advances that may follow from this.

Permalink | Tags: Physics, Quantum Information, Science

January 21, 2006

Experimentalist bloggers and Joule heating

Posted by Arcane Gazebo at 10:50 PM

Yesterday Chad Orzel speculated about the relative absence of experimental physicists in the blogging community. Unfortunately, I didn't have time to comment until now, because I was busy working in the lab. (Actually we were gearing up for, and then undergoing, a major safety inspection. The inspectors, who were reminiscent of the consultants from Office Space, stood around trying to invent scenarios under which a graduate student could suffer oxygen deprivation folowing sudden helium vaporization in our dilution fridge.)

Anyway, Chad's hypothesis was that theorists spend more time in front of computers on a daily basis, and thus blogging is just more convenient. This seems right to me: I'm one of the few condensed matter experimentalists who maintains a blog (and it probably helps that I'm a grad student rather than a postdoc or on the tenure track), and whether or not I have time to post mostly depends on how much time I'm spending on the computer, versus in front of an oscilloscope or soldering iron (or bolting power strips to desks two feet above the floor to satisfy safety inspectors).

For a period of about 10 months last year, we did not have an experiment running as we were fabricating a new sample. And due to the division of labor among the grad students on this project, I was not closely involved with the fabrication process, and instead spent my time reading papers, writing papers and reports to funding agencies, writing software, designing circuits, and doing simulations. These were all computer-intensive activities, and I was able to get a fair amount of blogging done. For the last two months, however, we've been doing measurements on the chip we made last year, and I've spent a lot of time taking data, looking at scope traces, and reconfiguring wiring. Hence, I think up a bunch of posts over the week and write them up on Saturday night, which is a bit lame.

Fortunately, I do frequently have the ability to post even under these conditions, due to the phenomenon of Joule heating: if a current I is applied to an electrical resistance at a voltage V heat will be dissipated at a rate equal to the product IV. Every time we make a measurement, we apply a current pulse to our device, which produces a voltage and a corresponding amount of heat. If this heat is allowed to accumulate on the chip, it will wipe out the quantum effects we're trying to study, so between each measurement we have to wait long enough for the chip to cool off. In practice, this means instead of taking a million measurements in a second we are reduced to about 2,000. Furthermore, to get good statistics and sweep over an interesting range of parameters we have to take a large number of measurements, so it turns out that to get interesting results we need to measure continuously for at least 12 hours. I've written an overly baroque computer program to automate all this, so once I know what I want to measure, I can push a button to start the experiment, do something else for a while (usually analyzing data from the previous run), and then collect all the data hours later (or the next day). (This is only when everything is working properly; otherwise it's back to the oscilloscope and wiring diagrams.) And in the gaps I can do a little blogging.

These days, the trend in the superconducting qubit community is towards nondissipative readout—i.e., measurements which leave the device in the superconducting state and thus produce no heat. This might threaten to take away my blogging windows, except that it would also enable measurements that require even better statistics and broader sweeps, and so there will still be reasons to do 12- and 24-hour runs. (Actually, our record is about 48 hours, but we don't currently have the battery life to repeat that.)

Permalink | Tags: Lab, Life, Physics, Quantum Information, Science

2006 March Meeting Abstract

Posted by Arcane Gazebo at 6:42 PM

Less than two months remain before the APS March Meeting, which in terms of blogging means more short posts at odd hours, when I'm not in the lab trying to gather lots of last-minute data. Here's the abstract for my talk:

Abstract: K40.00012 : Variable Coupling of Two Flux Qubits
5:06 PM–5:18 PM

T. Hime, P.A. Reichardt, B.L.T. Plourde, T.L. Robertson, C.-E. Wu, A.V. Ustinov, John Clarke

We report observations of variable coupling of two flux qubits. The qubits are coupled inductively to each other and to a readout Superconducting QUantum Interference Device (SQUID). By applying microwave radiation to the device, we observed resonant absorption in each of the qubits when the level splitting in the qubit matched the energy of the microwave photons. Using the two on-chip flux bias lines we adjusted the bias of each qubit so that the energy levels of the two qubits were equal; we then observed a splitting of the resulting absorption peak characteristic of coupling between the qubits. We varied the coupling between the qubits by changing the current bias in the SQUID in the zero voltage state, thereby changing its dynamic inductance and thus modifying the effective mutual inductance between the qubits. We compare the resulting changes in splitting with our predictions. This controllable coupling should be extendable to many qubits.


I'll do a post explaining this in more detail around the time of my talk; some of this work is still, uh, "in progress". (In fact we have performed all the experiments mentioned in the abstract, but we are working on collecting more/better data.) The talk immediately before mine covers some other results from these experiments.

Permalink | Tags: Physics, Publications, Quantum Information, Science

November 27, 2005

Useful Physics Aggregators

Posted by Arcane Gazebo at 4:34 PM

Those of you who come here for the physics blogging (which has been somewhat absent of late) may be interested in a couple of links I found recently, via referrals and Technorati:

Mixed States aggregates the RSS feeds of a number of physics blogs (including this one). Since the included bloggers are listed by their real name, it's a nice way to see who else in the community is blogging (although I didn't recognize any names that I knew from physics rather than from reading blogs).

Coherence * is a blog reviewing work in superconducting quantum computing, something that should be useful to me professionally (perhaps more so than the cond-mat RSS feed, which is high volume and a bit tough to sort by topic). Above their blogroll they list professors working in the field, including former Clarke group member and current collaborator Britton Plourde, but strangely not John Clarke himself. (However, there are at least four of John's former students/postdocs there, among other familiar names.)

Permalink | Tags: Internet, Physics, Quantum Information, Science

August 22, 2005

Follow-up on decoherence

Posted by Arcane Gazebo at 3:14 PM

One of the comments on the flux qubit post asked an important question: where does the decoherence come from? I dealt with this a bit in the thread itself, but this post will be a less technical treatment.

In general, decoherence is a result of the fact that the qubit under study isn't in isolation, but interacts with some larger environment. Through this interaction, information that starts out concentrated in the qubit dissipates out into the environment, and likewise information in the environment mixes into the qubit. Of course, the state of the environment isn't known beforehand so the information that mixes in just looks random, and averages out over a large number of experiments.

In the case of our qubit, what matters is the electromagnetic environment—the electric and magnetic fields that act on the qubit. Any fluctuations in these fields can produce decoherence, and just about everything produces some level of field noise.

Continue reading "Follow-up on decoherence"
Permalink | Tags: Lab, Physics, Quantum Information, Science

August 18, 2005

Publication: Flux qubits and readout device with two independent flux lines

Posted by Arcane Gazebo at 7:36 PM

This paper contains the major results of my graduate research so far, compressed into four pages. Instead of the abstract I'm posting something closer to a layman's explanation, which is below the fold since it got a bit long.

Flux qubits and readout device with two independent flux lines
B. L. T. Plourde, T. L. Robertson, P. A. Reichardt, T. Hime, S. Linzen, C.-E. Wu, and John Clarke
Phys. Rev. B 72, 060506(R) (2005)

Continue reading "Publication: Flux qubits and readout device with two independent flux lines"
Permalink | Tags: Lab, Physics, Publications, Quantum Information, Science