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Institute of Physics Institute of Physics

IoP colloquium: John Bollinger - National Institute of Standards and Technology (NIST USA)

Quantum dynamics and sensing with a 200-ion crystal stored in a Penning trap

John Bollinger is a staff scientist and current group leader of the NIST Ion Storage Group in the Time and Frequency Div. of the National Institute of Standards and Technology (NIST). He was a principal on early NIST studies employing laser-cooled ions for microwave frequency standards and then carried out studies on the collective and cold plasma behavior of laser-cooled ion crystals in Penning traps, including precise characterization of the plasma modes, crystal equilibria, and structural phase transitions. His recent work has focused on the use of trapped ion crystals of several hundred ions confined in Penning ion traps for quantum information studies, including quantum simulation and quantum metrology. John received undergraduate degrees in physics and mathematics from Cornell University in 1974, and a Ph.D. in physics from Harvard University in 1981. John is a Fellow of the American Physical Society (APS). Recent service includes serving on the chair line (2017-2021) of the Div. of Atomic, Molecular, and Optical Physics (DAMOP) of APS.
Date
2 November 2023
Time
16:00 -17:00
Location
Science Park 904
Room
C0.110

Title: Quantum dynamics and sensing with a 200-ion crystal stored in a Penning trap

Abstract: Controlling the quantum dynamics of mesoscopic objects is of intrinsic as well as practical interest.  I will describe experimental work implementing non-equilibrium quantum dynamics and sensing with laser cooled single-plane crystals of 200 ions stored in a Penning trap.  With an optical dipole force we couple the center-of-mass vibrational mode of the ion crystal with the collective electronic spin (qubit) degree of freedom of the ions.  This coupling can create entangled states of the ion crystal spin and center-of-mass motional degrees of freedom that can be used to engineer long-range quantum magnetic interactions between the ion spins.

In my talk I will focus on how spin-motion entangled states can also be used to sense weak motional excitations of the crystal center-of-mass mode.  By controlling the coherent dynamics of the entangled state via a many-body echo, a weak motional excitation of the ion crystal is mapped into a spin rotation, which we measure.  We demonstrate a sensitivity for measuring weak motional excitations of 8.8 ± 0.4 decibels below the standard quantum limit and a sensitivity for measuring electric fields of 240 ± 10 nanovolts per meter in 1 second [1]. Feasible improvements should enable the use of trapped ions in searches for axion dark matter.

[1] Gilmore et al., Science 373, 673 (2021).

Science Park 904

Room C0.110
Science Park 904
1098 XH Amsterdam