In a groundbreaking study published in Science, JILA and NIST Fellow Jun Ye and his research team have made significant strides in understanding the complex light-atom interactions within atomic clocks, renowned for their precision. By utilizing a cubic lattice, the researchers measured specific energy shifts in an array of strontium-87 atoms due to dipole-dipole interactions, known as cooperative Lamb shifts. These shifts were spectroscopically studied, spatially analyzed, and compared with calculated values using innovative imaging spectroscopy techniques developed in the experiment. The findings shed light on the intricate dynamics of dipole-dipole interactions within atomic clocks and offer insights crucial for enhancing their performance.
The study focused on cooperative Lamb shifts, crucial factors as atomic clocks continue to evolve with growing numbers of atoms. The researchers explored the spatial arrangement of strontium-87 atoms within a cubic lattice, creating a controlled environment to observe and manipulate dipole-dipole interactions with unprecedented precision. The researchers also examined the influence of dipole-dipole interactions on the clock system’s frequency shifts and detected cooperative Lamb shifts, small effects with significant implications for clock accuracy.
The researchers not only measured these shifts but also observed that cooperative Lamb shifts varied locally within the lattice, impacting the frequency at which atoms oscillate. This spatial dependence is a crucial systematic shift for clock precision, necessitating a deeper understanding. The study’s outcomes enable the calibration of clocks to be more accurate, enhancing timekeeping precision.
The team uncovered a close connection between cooperative Lamb shifts and the propagation direction of the clock probe laser within the lattice. This relationship allowed them to identify a specific angle where a “zero crossing” occurred, transitioning the frequency shift from positive to negative. By fine-tuning this angle, the researchers aimed to make the clock more robust against energy shifts, contributing to further advancements in clock technology.
Looking ahead, the researchers at JILA aspire to leverage dipole-dipole interactions within the cubic lattice to explore many-body physics in their clock system. This opens avenues for potential applications, including spin squeezing—a form of quantum entanglement—to enhance clock performance and delve into novel realms of physics
