Quantum Scientist
by Daniel Angfigures by Aparna Nathan Originally written for Harvard’s Science in the News (2018), reposted as original link has become dead. Particle physics says that the universe shouldn’t exist. This is a radical claim! But if the current theories that underlie particle physics are correct and complete, then the Big Bang that birthed the …
After almost eight years, my journey with the ACME experiment is finally coming to an end. On April 11, I will be defending my PhD dissertation titled “Progress on an Improved Measurement of the Electron Electric Dipole Moment”. This post provides an overview of what my thesis is about for a general audience, so that …
The following is just one physicist’s take on why preferring dark matter over MOND is not unreasonable. (Note that it is not meant to be authoritative in any way!) In the course of writing this post I came across this excellent recent review article (Bertone & Hooper 2018, History of Dark Matter) which has a more …
Today is the publication of the latest result from the experiment that I work on at Harvard, the Advanced Cold Molecule Electron Electric Dipole Moment, or ACME EDM (here is a link to read the paper in entirety). In this experiment, we seek to look for an asymmetry in the electron’s shape. What does that exactly mean …
What is the ACME EDM experiment? When one hears the word “acme”, what might come to mind is the Acme corporation in the Road Runner/Wile E Coyote cartoon series. Wile orders all kinds of products from the company to trip Road Runner, but these products almost inevitably fail. On the other hand, the word “acme” …
In our last post, we saw how the potential of atoms had been pushed to an incredible limit by the work of Commins and his group at Berkeley. Now, the 21st century had arrived, and technology was ready to start utilizing the power of molecules, which are nature’s built-in mini-laboratories for the electron. Nature’s Small …
Eugene Commins was one of the most influential atomic physicists of the latter half of the 20th century, not just through his experimental results, which were first-rate (including being one of the first to observe atomic parity violation), but most especially through his legacy of mentorship and teaching. His group at UC Berkeley produced a …
When we left off last time, we were in the middle of a drought: over two decades of no improvement in the upper limit of the electron EDM from that found by the last of the cesium beam experiments in 1968: This was not a bad number at all. In fact, using the classical electron …
Last week, we talked about how the pioneering papers in the 1950s and 60s of Purcell, Ramsey, and Sandars started off the decades-long search for imperfection in the electron’s shape, or the electron electric dipole moment (eEDM). This week, we’re going to cover some of the early beam experiments dedicated to measuring the electron EDM. …
As I’ve shared in a series of blog posts, I currently work on an experiment measuring the electric dipole moment (or EDM) of the electron. Colloquially, we like to call it the “shape” of the electron. (To be a little bit more accurate, it’s really the shape of the electric field produced by the electron.) …
Just this week an article in Nature was published featuring the new activities that the Gabrielse lab (where I work) is starting up at the newly-found Center for Fundamental Physics at Northwestern. In particular, the article highlights the growing importance of relatively small-scale “tabletop” experiments like ACME to probe for new physics beyond the Standard …
Why should we care about the existence of the electron electric dipole moment (EDM)? In a previous post, we established that the existence of an electron EDM would imply a violation of a symmetry in physics called CP-symmetry, or CP violation (CPV). But it isn’t clear why CPV has any importance beyond being something interesting …
In this series so far, we’ve discussed a lot about the physics of the ACME EDM experiment: the atomic physics methods we use to look for a small asymmetry in the electron’s charge distribution. However, we’ve never tackled the big question directly: why does the electron’s charge distribution matter at all? The precision achieved on the …
In our overview of the ACME experiment, we outlined the broad method of the experiment: we measure the deformation in the shape of the electron by performing spin precession on the molecule ThO. In the post about atomic structure, we outlined the basics of energy levels in a molecule, as well as that of ThO itself. …
In the first two general articles I wrote about the ACME EDM experiment, I outlined the basic goal of the experiment (to measure the electron electric dipole moment) and the broad principle of how we accomplish that (by performing a spin precession measurement on a molecule in an electric field). Here, I will get into …
A shorter introduction to the ACME EDM experiment can be found here. In the first introductory post of this series I outlined the immense precision of the ACME experiment in measuring the electron’s “shape.” A natural followup question is, how did we do that? In this post I will outline the basic measurement scheme in our …
Update, October 2018: This has now been superseded by a more informative and streamlined introduction here: Introducing the ACME EDM Experiment. It’s been almost two months since I last updated this blog, and the reason is because I’ve been utterly busy with both my courses and all the research going on in my experiment. As …