A Quantum Adventure

by Jorge Cham

How do you make something that has never existed before?

I often get suggestions for comics I should draw, which I welcome because A) I like to think of PHD Comics as a global collaborative effort and B) after 17 years, I’m almost out of ideas. This particular suggestion came from Chen-Lung Hung, a postdoc in Physics at Caltech:

PANEL 1 – Ask a scientist: “What motivates you to do the research you do?”

PANEL 2 – What people expect them to answer: “This can lead to real-life applications such as A, B, C, D, etc.”

PANEL 3 – How a real scientist would answer: “Because it’s cool.”


Ok, granted, the punchline needs work. Chen-Lung also asked me to make it clear that his research has important real-life applications, should someone from NSF, who funds his work, happen to be reading this blog.

Chen-Lung’s work with Prof. Jeff Kimble of Caltech’s IQIM is the subject of the third installment in our animated series of explanations of Quantum concepts and devices.

“The problem with atoms,” Prof. Kimble said at one point during our 3-4 hour conversation, “is that they exist in three dimensional space.” I didn’t know that was a problem (unless you expect them to exist in more than 3 dimensions), but Jeff explained that it means it’s very hard to control Quantum systems because the world is wide open, and information can leak and be corrupted from any direction. After a entire academic career making breakthroughs with one type of Quantum System, he’s now directing his group towards a new, experimental type which they believe has more potential for building devices with many Quantum Objects. As Jeff says in the video, “It’s a privilege to be able to explore.”


Shaping light, trapping atoms, alligator waveguides… The goal, Jeff and Chen-lung explained, is to make systems that are “surprising.” Not surprisingly, it was really hard to draw this video. How do you depict something that has never existed before? And more importantly, do you draw alligators differently from crocodiles? (Did you know alligators only exist in two places in the world: the Southern part of the United States, and in China?).


Hopefully, those of you watching will get some understanding of some key Quantum concepts and what it takes to build and manipulate Quantum systems, but to be honest, I make these videos because I think the work is really cool.

Jeff and Chen-Lung: thanks for taking us along on this adventure of yours, the privilege is all ours.

Watch the third installment of this series:

Jorge Cham is the creator of Piled Higher and Deeper (www.phdcomics.com).


Featuring: Jeff Kimble and Chen-Lung Hung
Animated by Jorge Cham

Produced in Partnership with the Institute for Quantum Information and Matter (http://iqim.caltech.edu) at Caltech with funding provided by the National Science Foundation and the Betty and Gordon Moore Foundation.

11 thoughts on “A Quantum Adventure

    • Quantum mechanics does not make common sense, as it is not common for us to observe quantum mechanics in action.

    • Wikipedia is not a better introduction. For example, Wikipedia says, “Because the known laws of physics are all local, and because nonlocal interactions combined with relativity lead to causal paradoxes, many physicists find this unacceptable.” The first part of that sentence is wrong. Quantum Mechanics is not local (and Bell’s inequality and the experiments of Aspect confirm that the world is not local). And, Bohmian Mechanics combined with relativity does not lead to causal paradoxes. It is true that different observers may disagree on which of two events is the cause and which the effect, but that does not produce a paradox. (And, other versions of Quantum Mechanics don’t avoid this; they just try not to mention it.)

      If you want to understand Bohmian Mechanics, you should read what the experts have written, e.g., Bell, Goldstein. See http://www.bohmian-mechanics.net and http://www.math.rutgers.edu/~oldstein/.

      Perhaps a “majority” of physicists do not support Bohmian Mechanics, but truth is not determined by majority rule. For some actual surveys on physicist’s belief, see http://arxiv.org/pdf/1306.4646. In particular, the discussion of Question 6 on page 9 is sad. If someone can’t understand what Bell wrote, or can’t be bothered to read it, then they shouldn’t get a vote. Bell’s book (“Speakable and Unspeakable in Quantum Mechanics”) is essential reading. (But, the foreword by Alain Aspect in the second edition sadly shows that Aspect didn’t actually read the book.) Also, see http://www.scholarpedia.org/article/Bell%27s_theorem.

      If “impartial” means giving nonsense equal time with sense, I’ll pass. The nonsense started with Bohr: See http://www.bohmian-mechanics.net/sokalhoax.html for a discussion of the history.

      I feel sorry for Schrödinger. He gave the example of his cat to show the absurdity of what Bohr and others were saying. Instead, people keep saying, “Wow! The cat is both alive and dead!” Um, no. It is still absurd to say that. And, it is not required by experiment or theory to say that. I’d want some pretty convincing evidence before I’d say something like that. Bohmian Mechanics doesn’t have any cats that are both alive and dead. Nor does it have electrons that are both waves and particles at the same time. Nor does it have photons that are half in one place and half in another.

      A recent experiment shows that photons follow Bohmian trajectories: “Observing the Average Trajectories of Single Photons in a Two-Slit Interferometer” by Sacha Kocsis et al., Science, vol. 332, June 3, 2011, pages 1170-1173. Compare Fig. 3 in the article with figure Fig. 1 on http://www.math.rutgers.edu/~oldstein/papers/qts/node4.html. Somehow, the authors of the Science article manage to avoid pointing out that they’ve confirmed Bohmian Mechanics.

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