Awards Database

Cottrell College Science Awards - 2014

Robert J. Clark

The Citadel

An investigation of the dynamics of ions confined within surface-electrode multipole Paul traps

These days we hear a lot about quantum information processing -- computing that depends on quantum effects, the seemingly weird physical phenomena present in the subatomic realm of atoms, electrons, and other particles.

Quantum computers may be able to perform vast numbers of calculations much faster than today’s computers. But to do so they will have to rely on quantum bits (qubits).

 A regular “bit,” of course, is the basic unit of computer information – in conventional computers it is represented by 1 or 0; a qubit, however, can exist as both 1 and 0 simultaneously. But achieving this strange state involves isolating to a challenging degree the physical system in which the qubits are encoded from its environment.

Robert J. Clark, assistant professor of physics at The Citadel, is attempting to develop a new type of “surface-electrode ion trap” – basically a device somewhat like a computer chip that traps the charged atoms (ions) that serve as a quantum computer’s qubits.

His work is based on the fundamental principles of a “Paul trap,” a jail of sorts for ions.

The trap employs radio-frequency electrical forces to imprison selected ions in a tiny space. Things begin to get interesting for qubit researchers when lasers are used to briefly zap the imprisoned ions. At first they grow excited by absorbing the light, but then when the laser is switched off, the ions give up slightly more energy than they’ve absorbed. Zap them enough times rapidly and the ions condense – or cool – into a well ordered crystalline phase.

Once the ions are crystallized, they become prime qubit material. Specifically, Clark and his students will investigate through elaborate computer simulations how crystalline ions in a Paul trap behave as they go through their quantum paces.

Of great concern to researchers is the annoying tendency of these tiny particles to move slightly due the effects of nearby electric forces.

While this is a chronic problem with certain types of traps, Clark intends to explore making improvements to a type called a “multipole ion trap.” It involves trapping and crystallizing ions in an invisible force field that resembles a box more than a bowl, a bowl being the shape of a standard Paul trap.

“This project will be an important part of the worldwide effort to ‘“build a better ion trap’ for quantum information,” Clark said. “It will also provide a thorough training for undergraduates in the methods of experimental and computational physics research.”

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