CQE PI Feature – John Chiaverini

Holding on to single ions to enable quantum computing and sensing

Featured in QSEC newsletter in summer 2021

Dr. John Chiaverini, a Senior Member of the Technical Staff at Lincoln Laboratory and a Principal Investigator in MIT’s Center for Quantum Engineering (CQE), is developing technology to enable quantum computing and sensing based on some of the best qubits in the world.

The qubits he and his team use are each housed in a single atomic ion.  A single ion of an element like strontium or calcium can be held electromagnetically, almost motionless in space, above the surface of specialized microchips in a vacuum chamber.  The ion is thus isolated from many of the deleterious influences of the environment that limit the coherence of most other qubit types.  Though ions themselves form naturally stable qubits, cajoling them into doing exactly what is needed for quantum computing and quantum-enhanced sensing requires applying control fields (typically laser beams, and in some cases radio-frequency or microwave signals), and this is where imperfections can be introduced, especially when considering independent control of multiple ions.

But Chiaverini is working to reduce those imperfections and make it possible to coordinate the control of arrays of individual ion qubits robustly and with low error.  Doing so may lead to systems which can serve as highly sensitive probes of beyond-standard-model effects, such as is the search for ultra-light dark matter.  Or they may be used to explore the fundamental behavior of multi-component entangled states, teasing apart the paradox of Schroedinger’s simultaneously alive-and-dead cat.  Or they can lay the foundation for practical quantum computers, processors that have the potential to speed up certain optimizations and accelerate the development of novel materials and the understanding of complex systems.

Growing up near Pittsburgh, Pennsylvania, a hilly area with hundreds of bridges over ravines and rivers, Chiaverini was first enticed by engineering; designing and building things that work became an enduring passion.  Taking up experimental physics for his degrees was not a significant departure, since the fields depend on one another synergistically.  Performing precision experiments to explore gravity at small length scales in graduate school at Stanford University required many disparate skills, including microfabrication, coherent optics, and cryogenics.  Moving into quantum information science, Chiaverini applied these and related techniques to the development of trapped-ion quantum information processors as a postdoc at the National Institute of Science and Technology in Boulder, Colorado.  Catching the quantum-computing bug, he never looked back.  He hopes to continue to push the boundaries of the engineering of quantum systems.

The trapped-ion team at Lincoln Laboratory collaborates closely with campus groups, in particular those of Prof. Isaac Chuang and Prof. Rajeev Ram, through the CQE, to explore new technologies and techniques for high-fidelity ion-state manipulation.  Along with these researchers, Chiaverini investigates integrated optical and electronic methods for more-precisely controlling ion qubits, as well as novel ion-state quantum encodings and the sensing algorithms that that they may enable, among several related areas.  New ideas can be flexibly pursued on the campus side of the joint Lincoln-MIT team; those that are viable can be adapted for integration into the multi-ion systems being engineered using Lincoln’s microfabrication capabilities.  In turn, advanced chip-scale ion traps with integrated control for collections of ions can be utilized on campus in the next wave of scientific inquiry, to allow more complex functionality with each step.  MIT students working with Chiaverini, both on campus and at Lincoln, enable much of this foundational quantum engineering.

Chiaverini believes that advances in quantum science and engineering will bear fruit in many areas over the coming years, with applications to metrology and positioning in the near term, the realization of practical quantum computing more long term, and enabling technology for basic science being continually developed along the way.  The field is just getting off the ground, and the ramifications are likely to be far-reaching, though it’s not yet known exactly where the biggest impacts will be.  In the meantime, the physicist in Chiaverini loves having the ability to manipulate quantum systems while trapping individual atoms, while the engineer in him will keep pushing to make them practically functional.