Welcome to Wes Campbell's Reseach Group at UCLA Physics & Astronomy
Our research uses ultra-cold atoms and molecules to learn about the physical processes that permeate our world.
We are specifically focused on the physics of quantum information, which includes advanced sensing, simulation, and computing applications.
We use gas and liquid phase atoms and molecules as tiny computers to perform tasks that cannot be simulated on classical computers. Our approach is to focus on novel species and novel ways to control them to leverage the built-in "quantumness" of these molecules for higher performance in these applications.
Latest News
Quantum Error Correction in Single Atoms
December 23, 2024: Quantum computers process analog information, and are therefore highly susceptible to noise. Quantum error correction (QEC), which "digitizes" the process, allows a perfect computation to be performed by an imperfect device (a feature not available with classical analog computing). Unfortunately, QEC tends to be costly, requiring many extra atoms in atomic processors. To address this, we have recently introduced QEC codes that are hosted within single atoms and tailored specifically to electromagnetic errors, which are the dominant type that occur in atomic processing.
Liquid-phase magnetometry
August 9, 2024: Atomic vapor cells can be employed for high-precision measurement of magnetic fields, but their vapor density cannot be increased arbitrarily without compromising their sensitivity. In a recently-published article in Science, we intorduce a liquid-phase molecular solution that may allow much higher spin densities than vapor cells. The trade-off is that these molecular systems have substantial broadening from interactions with the solvent. Whether these problems can be overcome remains a topic of current research.
Matter-wave Interferometry
March 30, 2024: One of the strange features of quantum mechanics is that it predicts how particles can behave like waves, which means they exhibit interference. A recently-published article describes how matter wave interferometry with a single trapped ion can be used to verify entanglement between the motion of the atom and its spin. The atom is split into two wavepackets (one for each spin state) that are separated (thereby erasing the spin coherence) and then recombined (reviving the spin coherence). Since the timescale of the entalging operation, about 16 picoseconds, is much shorter than the spin precession time, about 1 ns, this ``ultrafast'' entangling operation lays the groundwork for quantum gates with trapped ions that are orders of magnitude faster than the standard scheme.
``Cooling by
heating''
March 6, 2024: Laser cooling of an atom is
typically performed with narrow-linewidth laser light that
represents a highly-ordered (i.e. ``cold'') state of the
electromatnetic field. It may be tempting to ascribe the
resulting low atomic temperature to some sort of equilibrium
between the atom's state and this low-entropy state of the
electromagnetic field. In a new paper, we describe how the narrow-linewidth
part of the laser-cooling process can be separated from the
step that drives entropy removal, which illustrates that
even a hot, thermal state of the electromagnetic field (such
as sunlight) can
be used to cool the atom by coupling it to near-vacuum modes.