Caleb Knoernschild

Independent individual addressing of multiple neutral atom qubits with a micromirror-based beam steering system

We demonstrate a scalable approach to addressing multiple atomic qubits for use in quantum information processing. Individually trapped R87b atoms in a linear array are selectively manipulated with a single laser guided by a microelectromechanical beam steering system. Single qubit oscillations are shown on multiple sites at frequencies of ≃3.5u2002MHz with negligible crosstalk to neighboring sites. Switching times between the central atom and its closest neighbor were measured to be 6–7u2002μs while moving between the central atom and an atom two trap sites away took 10–14u2002μs.

Multiscale optics for enhanced light collection from a point source

High-efficiency collection of photons emitted by a point source over a wide field of view (FoV) is crucial for many applications. Multiscale optics offer improved light collection by utilizing small optical components placed close to the optical source, while maintaining a wide FoV provided by conventional imaging optics. In this work, we demonstrate collection efficiency of 26% of photons emitted by a pointlike source using a micromirror fabricated in silicon with no significant decrease in collection efficiency over a 10 mm object space.

MEMS-based optical beam steering system for quantum information processing in two-dimensional atomic systems

To provide scalability to quantum information processors utilizing trapped atoms or ions as quantum bits (qubits), the capability to address multiple individual qubits in a large array is needed. Microelectromechanical systems (MEMS) technology can be used to create a flexible and scalable optical system to direct the necessary laser beams to multiple qubit locations. We developed beam steering optics using controllable MEMS mirrors that enable one laser beam to address multiple qubit locations in a two-dimensional trap lattice. MEMS mirror settling times of approximately 10 micros were demonstrated, which allow for fast access time between qubits.

Multiplexed broadband beam steering system utilizing high speed MEMS mirrors.

We present a beam steering system based on micro-electromechanical systems technology that features high speed steering of multiple laser beams over a broad wavelength range. By utilizing high speed micromirrors with a broadband metallic coating, our system has the flexibility to simultaneously incorporate a wide range of wavelengths and multiple beams. We demonstrate reconfiguration of two independent beams at different wavelengths (780 and 635 nm) across a common 5x5 array with 4 micros settling time. Full simulation of the optical system provides insights on the scalability of the system. Such a system can provide a versatile tool for applications where fast laser multiplexing is necessary.

Investigation of Optical Power Tolerance for MEMS Mirrors

Optical power tolerance on micromirrors is a critical aspect of many high-power optical systems. Absorptive heating can negatively impact the performance of an optical system by altering the micromirrors curvature during operation. This can lead to shifts in the beam waist locations or imaging planes within a system. This paper describes a scheme to measure the impact of mirror heating by optical power and determine the power tolerances of micromirrors with gold and aluminum coatings using a 532-nm laser. Results are compared with an analytical model of thermally induced stress and optical absorptive heating. Experimental data shows that gold-coated mirrors are able to handle 40 mW of optical power with a beam waist displacement of less than 20% of the output Rayleigh length, while aluminum-coated mirrors can tolerate 125 mW. Measured data along with modeling suggest that, with proper metal coating, optical powers greater than 1 W should not adversely affect the system performance.

Stable optical phase modulation with micromirrors

We measure the motional fluctuations of a micromechanical mirror using a Michelson interferometer, and demonstrate its interferometric stability. The position stability of the micromirror is dominated by the thermal mechanical noise of the structure. With this level of stability, we utilize the micromirror to realize an optical phase modulator by simply reflecting light off the mirror and modulating its position. The resonant frequency of the modulator can be tuned by applying a voltage between the mirror and an underlying electrode. Full modulation depth of ±π is achieved when the mirror resonantly excited with a sinusoidal voltage at an amplitude of 11 V.

Enhanced Light Collection from a Point Fluorescent Source Using Multiscale Optics

We have demonstrated enhancement of point source light collection by a factor of 18 over a traditional f/2.55 imaging system (~17%) across a 15 mm object space by integrating a high numerical aperture micromirror.

Integrated optics technology for quantum information processing in atomic systems

Scalable quantum information processing in ion traps or neutral atoms requires highly integrated and functional optical systems for qubit manipulation and detection. We discuss and demonstrate integrated optics technologies that are relevant for this application.

Design and Characterization of MEMS Micromirrors for Ion Trap Quantum Computation

To build a large-scale quantum information processor (QIP) based on trapped ions or neutral atoms, integrated optical systems capable of delivering laser beams to multiple target locations are necessary. We consider a beam-shifting element consisting of a tilting micromirror located at the focal point of a lens, as a fundamental building block for such a system. We explore the design space of the micromirrors and characterize their dc, frequency, and transient responses. The fastest mirror features the resonant frequency of 113 kHz and the 98% settling time of 11 mus. The design tradeoffs are discussed to facilitate further optimization of the mirror performance for this application

Integrated Optics Technology for Ion Trap Based Large-Scale Quantum Information Processors

Realizing ion trap based large-scale quantum information processor requires integrated optics technologies. We design and characterize basic optical beam steering system using micromirrors as a first step towards constructing high-quality functional integrated optics.