Atoms make better quantum computers.
At its core, a quantum computer is a machine that uses a quantum system, like the spin of an electron, to do a very specific type of math.
This math takes advantage of the uniquely complex behavior of quantum systems, namely entanglement and superposition, to perform calculations that are fundamentally unlike the calculations ordinary computers based on classical physics can perform. Once quantum computers are powerful and stable enough, their unique computational power will solve world-changing problems that are beyond the capabilities of even the largest supercomputers.
Many quantum hardware developers use "synthetic" quantum systems for their quantum bits (qubits for short), like loops of supercooled superconducting wire, intentional imperfections in crystalline silicon, or other designs carefully coaxed to behave as quantum systems. At IonQ, we take a different approach. We use a naturally occurring quantum system: individual atoms.
These atoms are the heart of our quantum processing units. We trap them in 3D space, and then use lasers to do everything from initial preparation to final readout. It requires counterintuitive physics, precision optical and mechanical engineering, and fine-grained firmware control over a variety of components, but the superior results speak for themselves.
Read on to understand exactly how our trapped ion quantum cores work, and why they’re the most promising platform for quantum computing in development today.
The Atom: Nature’s Qubit
The most important part of any quantum computer are its quantum bits, or qubits. IonQ’s qubits are ionized ytterbium atoms, a silvery rare-earth metal. Each ytterbium atom is perfectly identical to every other ytterbium atom in the universe.
Moreover, once prepared in a particular stable quantum state, they can remain in that state for very long periods of time — they're so consistent they're used in one of the most accurate atomic clocks ever built.
Bits vs Qubits
In a classical computer, the smallest unit of computation is called a bit. A bit can be in only one of two possible states: one or zero. A qubit has the ability to be in a complex superposition of these states,This is often described as being a probabilistic mix of zero and one at the same time, i.e. 50% zero + 50% one. This is a helpful simplification, but in reality, a complex superposition is different from (and computationally more powerful than) a simple probability distribution. For more on this idea, have a look at this comic. allowing for a much larger computational space — imagine only being able to point at the north or south pole, versus being able to point anywhere on the globe.