Quantum technology often requires the precise control of individual particles, atoms, or ions. Optical tweezers are one such device that can be used to control these particles.<\/p>\n
Optical tweezers use focused lasers to trap and control single atoms or ions with extremely high precision. They are used in quantum computing systems<\/a>, atomic clocks, and studying quantum physics.<\/p>\n However, trapped ions or atoms have a natural motion or jiggle due to thermal energy. This is even present when the particles are cooled to extremely low temperatures.<\/p>\n This jiggling introduces noise in the system, which interferes with the quantum information contained in the system.<\/p>\n Now, researchers from Caltech have turned this problem into a powerful resource. In a new study, the researchers use atomic motion to create hyperentanglement, a correlation of two properties simultaneously.\u00a0<\/p>\n In regular quantum entanglement, two particles are correlated through one property, like spin. However, in the case of hyperentanglement, it can be multiple properties.<\/p>\n This is the first demonstration of hyperentanglement in massive particles or neutral atoms<\/a>, previously seen with photons.<\/p>\n Harnessing motion for quantum information<\/p>\n To create hyperentanglement, the researchers use arrays of strontium atoms trapped using optical tweezers.<\/p>\n These atoms had thermal motion, which they wanted to turn into a controllable quantum resource.<\/p>\n They cooled the atoms to a near-complete standstill using a new method. This cooling method was inspired by Maxwell\u2019s demon<\/a>, a thought experiment from 1867.<\/p>\n In essence, the method involves measuring the motion of each atom and applying specific operations to eliminate the thermal motion. The decision is made one atom at a time based on real-time measurements.<\/p>\n Next, the researchers induce controlled oscillations in the atoms. This was done in such a way that the atoms could oscillate in two different motions simultaneously, creating a state of superposition. In simple terms, each atom can oscillate in two ways at the same time.\u00a0<\/p>\n These oscillations have a small amplitude of around 100 nanometers, much smaller than the width of a human hair.<\/p>\n Following this, the researchers entangle neighboring atoms. This induces a correlated state between the atoms\u2019 motional and electronic components. It\u2019s like twins separated at birth who share the same name and the same type of car.<\/p>\n Improving performance\u00a0<\/p>\n The cooling method, termed \u201cdetection and subsequent active correction of thermal motional excitations,\u201d outperforms the best laser-based cooling methods today.<\/p>\n Co-author Prof. Manuel Endres at Caltech spoke of their work in a press release<\/a>. \u201cBasically, the goal here was to push the boundaries on how much we could control these atoms,\u201d said Prof. Endres.<\/p>\n \u201cWe are essentially building a toolbox: We knew how to control the electrons within an atom, and we now learned how to control the external motion of the atom as a whole. It\u2019s like an atom toy that you have fully mastered.\u201d<\/p>\n The improved method could improve the performance of some quantum computers, which use trapped atoms as qubits.<\/p>\n