A team of quantum physicists at Caltech demonstrated that they can use individually controlled alkaline-earth atoms to achieve a hallmark of quantum computing: entanglement. This seemingly paradoxical phenomenon occurs when two atoms remain intimately connected even when separated by vast distances. Entanglement is essential to quantum computers because it enables the computers’ internal “switches,” known as qubits, to be correlated with each other and to encode an exponential amount of information.
“Essentially, we are breaking a two-qubit entanglement record for one of the three leading quantum science platforms: individual neutral atoms,” says Manuel Endres, an assistant professor of physics and leader of the Caltech team. Endres is also a member of one of three new quantum research institutes established by the National Science Foundation’s (NSF’s) Quantum Leap Challenges Institutes program, and a member of one of five new Department of Energy quantum science centers.
“We are opening up a new tool box for quantum computers and other applications,” says Ivaylo Madjarov, a Caltech graduate student and lead author of the new study. “With alkaline-earth atoms, we have more opportunities for manipulating systems and new opportunities for precise manipulation and readout of the system.”
To achieve their goal, the researchers turned to optical tweezers, which are basically laser beams that can maneuver individual atoms. The team previously used the same technology to develop a new design for optical atomic clocks. In the new study, the tweezers were used to persuade two strontium atoms within an array of atoms to become entangled.