Two millimeter-sized spheres containing a quintillion atoms each have been linked together in a single, shared quantum state.
Quantum entanglement is usually a fragile connection between two individual atoms or electrons. This new method uses a superconducting qubit to entangle the magnetic modes of two macroscopic objects you can actually see. These spheres contain more than ten to the power of eighteen spins, yet they behave as a single unified quantum entity. This experiment pushes the boundary of where the strange rules of quantum mechanics stop and the normal rules of the everyday world begin. It suggests that we could eventually build quantum networks using large-scale mechanical components. This brings us one step closer to quantum computers that look more like industrial machines than laboratory experiments.
Macroscopic entanglement between two magnon modes via two-tone driving of a superconducting qubit
arXiv · 2605.06297
The cavity-mediated coupling between magnons in an yttrium-iron-garnet (YIG) sphere and a superconducting qubit has recently been demonstrated as a new platform for preparing macroscopic quantum states. Here, based on this system, we propose to entangle two magnon modes in two YIG spheres by driving the qubit with a two-tone field and by appropriately choosing the frequencies and strengths of the two driving fields. We show that strong entanglement can be achieved with fully feasible parameters.