New swap-gate breakthrough puts superpowerful quantum computing within reach The researchers achieved 99.1 percent precision for their swap gates featuring 17,000 qubit pairs. Researchers at ETH Zurich have taken us a step closer to quantum supercomputers after achieving a major breakthrough with neutral-atom qubits, making them more stable during operation than ever before. To do so, the research team also had to develop a new type of quantum operation, which advances quantum computing. Quantum computers are considered the next frontier of computing, allowing computations at speeds that can’t be achieved by conventional silicon-based computers. Central to this capability of quantum computers are quantum bits or qubits that can exist in states of 0, 1 or a combination of both, known as a superposition. Quantum computers also use computing gates that allow qubits to be shuffled between these states and to run computations in parallel. One such gate critical to quantum operation is the swap gate, which allows two qubits to exchange their quantum states. What makes gates unreliable? To operate, swap gates rely on the tunnel effect, where particles can slip through obstacles in ways classical physics cannot comprehend, while quantum computers also use highly excited electronic states of atoms. All this depends on the strength and tunability of lasers, which suspend the atoms that make up qubits. Any fluctuations in the timing or strength of the lasers introduce errors into the system, making these gates unreliable. While errors with conventional bits are often seen as one in a trillion, they are more common with qubits, where the rate is one in a thousand. To overcome this, researchers at ETH Zurich used a subtler effect called the geometric phase, which exploits the path taken by atoms through an artificial ‘crystal of light’ built from intersecting laser beams. “Laser light is