We introduce and characterize a flexure-tuned optomechanical system in which a membrane is positioned microns from one end mirror of a Fabry-Perot optical cavity. By gently flexing the membrane's silicon frame (to 80 m radius of curvature (ROC)), we access the full range of optomechanical couplings predicted by a 1D scattering model; by more aggressively flexing (to 3 m ROC) we demonstrate >15 µm membrane travel, ∼ milliradian tilt tuning, and a wavelength-scale (1.64±0.78 µm) mirror-membrane separation. This passively-aligned, monolithic geometry will greatly simplify the tasks of mechanical and laser stabilization, and provides a platform for realizing flexure-tuned, wavelength-scale "membranein-the-middle" (MIM) systems and wavelength-scale two-membrane cavities for nested optomechanical systems. Finally, we provide analytical expressions for the leading-order optomechanical couplings, finding that this system can generate linear dissipative and quadratic dispersive strong coupling parameters that are orders of magnitude larger than is possible with a MIM geometry. Additionally, this system can achieve purely quadratic dispersive coupling with suppressed linear dissipative back-action, thereby reducing unwanted force noise and alleviating the requirement of single-photon strong coupling for resolving a membrane's phonon number states. * vincent.

We have developed a trapped ion system for producing two-dimensional (2D) ion crystals for applications in scalable quantum computing, quantum simulations, and 2D crystal phase transition and defect studies. The trap is a modification of a Paul trap with its ring electrode flattened and split into eight identical sectors and its two endcap electrodes shaped as truncated hollow cones for laser and imaging optics access. All ten trap electrodes can be independently DC-biased to create various aspect ratio trap geometries. We trap and Doppler cool 2D crystals of up to 30 Ba+ ions and demonstrate the tunability of the trapping potential both in the plane of the crystal and in the transverse direction.

We present the design and vacuum performance of a compact room-temperature trapped ion system for quantum computing, consisting of an ultra-high vacuum (UHV) package, a micro-fabricated surface trap, and a small form-factor ion pump. The system is designed to maximize mechanical stability and robustness by minimizing the system size and weight. The internal volume of the UHV package is only ≈2 cm3, a significant reduction in comparison with conventional vacuum chambers used in trapped ion experiments. We demonstrate trapping of 174Yb+ ions in this system and characterize the vacuum level in the UHV package by monitoring both the rates of ion hopping in a double-well potential and ion chain reordering events. The calculated pressure in this vacuum package is ≈2.2×1011 Torr, which is sufficient for the majority of current trapped ion experiments.

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We propose an optical scheme to generate an entangled state between a trapped ion and a solid state donor qubit through which-path erasure of identical photons emitted from the two systems. The proposed scheme leverages the similar transition frequencies between In donor bound excitons in ZnO and the P21/2 to S21/2 transition in Yb+. The lifetime of the relevant ionic state is longer than that of the ZnO system by a factor of 6, leading to a mismatch in the temporal profiles of emitted photons. A detuned cavity-assisted Raman scheme weakly excites the donor with a shaped laser pulse to generate photons with a 0.99 temporal overlap to the Yb+ emission and partially shift the emission of the defect toward the Yb+ transition. The remaining photon shift is accomplished via the dc Stark effect. We show that an entanglement rate of 2.1×104 s−1 and an entanglement fidelity of 94% can be attained using a weak excitation scheme with reasonable parameters.