NIST Adds to Quantum Computing Toolkit with Mixed-atom Logic Operations

Estimated reading time: 2 minutes

If they can be built, quantum computers could solve problems now considered intractable, such as breaking today's best data encryption codes. The same NIST group has demonstrated many other building blocks for quantum computers based on trapped ions. For example, the group demonstrated the first quantum logic gate (a CNOT gate) on individual qubits in 1995 using a single beryllium ion.

NIST's latest techniques provide a complete or "universal" set of quantum gates--meaning they could perform any possible computation--using ions of multiple elements. A universal set of quantum gates is one of the so-called DiVincenzo criteria, which describe the elements needed to build a practical quantum computer.

NIST's new mixed-atom gates could also help make better simulators to model quantum systems and could enable faster and simpler measurements in applications such as NIST's experimental quantum logic clock.

The mixed-atom gates rely on NIST's technique for entangling ions demonstrated more than a decade ago. Multiple carefully tuned laser beams apply an oscillating force to a pair of ions. If the ions are in different internal states, they feel different laser forces that alter the ions' external motions. This coupling of internal states with external motions has the effect of entangling the ions.

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