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Precision Measurement | Quantum Information Science & Technology

New Spin-Squeezing Techniques Let Atoms Work Together for Better Quantum Measurements

Opening new possibilities for quantum sensors, atomic clocks and tests of fundamental physics, JILA researchers have developed new ways of “entangling” or interlinking the properties of large numbers of particles. In the process they have devised ways to measure large groups of atoms more accurately even in disruptive, noisy environments.

The new techniques are described in a pair of papers published in *Nature.* JILA is a joint institute of the National Institute of Standards and Technology (NIST) and the University of Colorado Boulder.

Quantum Information Science & Technology

Seeing Quantum Weirdness: Superposition, Entanglement, and Tunneling

Quantum science promises a range of technological breakthroughs, such as quantum computers that can help discover new pharmaceuticals or quantum sensors for navigation. These capabilities rest on two unusual properties of quantum systems, superposition and entanglement. Just as a computer register stores information in the zeros or ones of classical bits, quantum bits, or qubits, store quantum information—but in the quantum world, superposition allows the qubit to be *both a zero and a one at the same time*. Furthermore, multiple qubits can be bizarrely correlated through a process called entanglement. When two qubits are entangled with each other, each qubit individually looks to be in a random state, but measuring one qubit reveals perfect information about its entangled partner. These properties of superposition and entanglement make qubits quite special, as they can work more efficiently than a classical computer’s bits.

However, a common challenge in actually using these quantum systems arises due to their limited memory time, or “coherence” time, which is often measured in milliseconds. Many researchers at JILA study and use superposition and entanglement of quantum systems, including JILA fellow Adam Kaufman. Previously, Kaufman and his research team focused on improving the coherence time of the strontium atoms’ superposition between the ground state and the “clock” state, so named because these two states form the basis for state-of-the-art atomic clocks. As reported in two new papers, researchers from this lab have extended these studies to much larger system sizes, with an atom in a superposition of hundreds of locations, and separately, demonstrating optical clock entanglement with seconds-scale coherence time.

Precision Measurement | Quantum Information Science & Technology

Tweezing a New Kind of Qubit

JILA has a long history in quantum research, advancing the state of the art in the field as its Fellows study various quantum effects. One of these Fellowsis Adam Kaufman. Kaufman and his laboratory team work on quantum systems that are based on neutral atoms, investigating their capacities for quantum information storage and manipulation. The researchers utilize optical tweezers—arrays of highly focused laser beams which hold and move atoms—to study these systems. Optical tweezers allow researchers exquisite, single-particle experimental control. In a new paper published in *Physical Review X*, Kaufman and his team demonstrate that a specific isotope, ytterbium-171 (171Yb), has the capacity to store quantum information in decoherence-resistant (i.e., stable) nuclear qubits, allows for the ability to quickly manipulate the qubits, and finally, permits the production of such qubits in large, uniformly filled arrays.

Atomic & Molecular Physics | Laser Physics | Precision Measurement

Tweezing a New Kind of Atomic Clock

Using optical tweezers, the Kaufman and Ye groups at JILA have achieved record coherence times, an important advance for optical clocks and quantum computing.

Atomic & Molecular Physics

The Strontium Optical Tweezer

JILA researchers have, for the first time, trapped a single alkaline-earth atom and cooled it to its ground state. To trap this atom, researchers used an optical tweezer, which is a laser focused to a pinpoint that can hold, move and manipulate atoms. The full motional and electronic control wielded by this tool enables microscopically precise studies of the limiting factors in many of today’s forefront physics experiments, especially quantum information science and metrology.