Arrays of alkaline-earth atoms offer optical-clock qubits with long coherence times, scalability to large qubit numbers, and tunable Rydberg-mediated interactions. These features provide an ideal setting for exploring how microscopic control and entanglement can improve the performance of optical atomic clocks beyond conventional limits. This talk will cover two efforts in this area: recent results from JILA demonstrating entanglement-enhanced optical-clock operation, and a brief introduction to a new effort at Caltech towards next-generation quantum metrology with neutral-atom arrays.
Arrays of alkaline-earth atoms offer optical-clock qubits with long coherence times, scalability to large qubit numbers, and tunable Rydberg-mediated interactions. These features provide an ideal setting for exploring how microscopic control and entanglement can improve the performance of optical atomic clocks beyond conventional limits. This talk will cover two efforts in this area: recent results from JILA demonstrating entanglement-enhanced optical-clock operation, and a brief introduction to a new effort at Caltech towards next-generation quantum metrology with neutral-atom arrays.
Programmable arrays of alkaline-earth atoms have emerged as a versatile experimental platform for quantum science. Together with Rydberg interactions, control at the single-particle level makes such atom arrays ideal systems for studying how quantum entanglement can be harnessed to improve the performance of optical atomic clocks. In this talk, I will discuss recent work from JILA, where we have achieved this goal by engineering Rydberg interactions to prepare entangled states with metrological gain.
Neutral atoms trapped in arrays of optical tweezers are a versatile platform for multiple research efforts in quantum information science. In particular, alkaline-earth atoms like Yb offer many advantages including ultralong coherence nuclear spin states for quantum information storage and high-fidelity qubit operations, optical transitions to Rydberg states for generating strong, long-range interactions between atoms, and narrow optical transitions for efficient cooling and metrology. Additionally, optical transitions from the long-lived 3P0 nuclear spin state have frequencies in the telecommunications band making integration with fiber networks and silicon nanophotonics an attractive avenue of exploration for hybrid quantum systems and quantum communication. Finally, these optical tweezer platforms are well suited for investigating the cooperative response of an array of atoms, where the proximity of neighboring atoms fundamentally alters the systems optical response which has implications for quantum information storage. Here I will present efforts to investigate these research avenues using alkaline-earth atoms in optical tweezers.
Alkaline-earth tweezer arrays have emerged as a powerful technology for both quantum computing and sensing, due to several internal degrees of freedom for flexible error-correction, and optical clock transitions. Efficient and scalable coupling of single atoms in an array to single photons is a major outstanding challenge. With alkaline earth atoms, such an interface would enable error-correction and quantum networking of optical clocks. I will describe a new kind of macroscopic lens based optical resonator which can have wavelength scale mode waists, and thus strong coupling even at very low finesse. I will show how to make arrays of such resonators, naturally well-suited for coupling with atom arrays – in the context of our efforts to make “cavity-atom arrays” of Ytterbium, providing a scalable and parallel link to single photons, for error-corrected sensing, as well as networking of atomic clocks.
Ultra-cold atoms in optical lattices provide a versatile and robust platform to study fundamental condensed-matter physics problems and have applications in quantum optics as well as quantum information processing. For many of these applications, Rydberg atoms (atoms excited to large principal quantum numbers) are ideal due to its long coherence times and strong interactions. However, one of the pre-requisite for such applications is identical confinement of ground state atoms with Rydberg atoms. This is challenging for conventionally used alkali atoms. In this thesis, I discuss the potential of using alkaline-earth Rydberg atoms for many-body physics by implementing simultaneous trapping for the relevant internal states. In particular, I consider a scheme for generating multi-particle entanglement and explore charge transport in a one dimensional atomic lattice.
The optical clock states of alkaline earth and alkaline earthlike atoms are the fundament of state-of-the-art optical atomic clocks. An important prerequisite for the operation of optical clocks is the magic trapping conditions where electronic and motional dynamics decouple. Here, we identify and experimentally demonstrate simultaneous magic trapping for two clock transitions in ^{88}Sr, realizing so-called triple-magic conditions at a specially chosen magic angle. Under these conditions, we operate an all-optical qutrit comprising the ground state ^{1}S_{0}, and the two metastable clock states ^{3}P_{0} and ^{3}P_{2}. We demonstrate fast optical control in an atom array using two- and three-photon couplings to realize high-fidelity manipulation between all qutrit states. At the magic angle, we probe the coherence achievable in magic-angle-tuned traps and find atom-atom coherence times between the metastable states as long as 715(30) ms. Our work opens several new directions, including qutrit-based quantum metrology on optical transitions and high-fidelity and high-coherence manipulation on the ^{88}Sr fine-structure qubit.
Neutral atom arrays have rapidly emerged as a leading platform for quantum computing, boasting scalable, configurable arrays of single atoms trapped in optical tweezers, fast, high-fidelity entangling gates through Rydberg interactions, and programmable, parallelized control of qubit operations. Coupling an atom array to an optical cavity opens a new frontier. Leveraging enhanced light-atom interactions in cavity quantum electrodynamics, cavity- coupled atom arrays acquire capabilities that can further expand the neutral atom toolbox, including cavity-enhanced atom readouts, atom-photon entanglement, and photon-mediated interactions between distant atoms. This thesis presents a quantum hardware platform that integrates an array of neutral atoms with a high-finesse optical cavity. After describing the design and development of the experimental apparatus, I demonstrate high-fidelity atom state readout through the cavity, achieving improved speed and atom survival compared to conventional free-space imaging methods. I then introduce a new technique for selectively controlling atom-cavity coupling on arbitrary subsets of the array, using local AC Stark shifts on the excited states of the atoms. Building on these tools, I demonstrate fast, non-destructive cavity-based readout of atom arrays, a crucial bottleneck of atom array platforms. I also showcase real-time measurement and feedback capabilities with a demonstration of classical error correction, using a register of atomic bits. Finally, I describe progress toward implementing single- and two-qubit gates within the cavity-coupled system. By combining coherent control, tunable interactions, and high-fidelity, non-destructive readout integrated and real-time feedback, the cavity-coupled Rydberg atom array offers a promising path toward fault-tolerant quantum computing.