Program

LSU SQuInT Event Map

SESSION 11: Ions (Theatre)

Chair: (Boerge Hemmerling (UC Berkeley))
10:15am - 11:00amChristopher Ballance, Oxford
Techniques for scaling trapped-ion QIP

Abstract. Demonstration experiments on small numbers of qubits are approaching the fidelity needed for large scale computation. However scaling these systems to the size needed to build a useful quantum computer presents significant challenges. We are mounting a two-pronged attack on these challenges for trapped-ion systems: using microwave control fields instead of lasers to simplify the control requirements, and pursing a networked modular scheme based on many simple nodes with complexity close to the current state of the art. Here we present the realization of high-fidelity single- and two-qubit gates (99.9999% and 99.7% respectively) driven with microwaves generated by electrodes embedded in the ion-trap chip, and discuss the potential for scaling this design. Furthermore, we present initial results on a modular architecture, involving mapping information from a memory qubit to an interface qubit, and from an interface qubit to a photon.

11:00am - 11:30amDietrich Leibfried, NIST, Boulder
Preparation and coherent manipulation of pure quantum states of a single molecular ion

Abstract. An amazing level of control is routinely reached in modern experiments with atoms, but similar control over molecules has been an elusive goal. We recently proposed a method based on quantum logic spectroscopy [1] to address this problem for a wide class of molecular ions [2]. We have now realized the basic elements of this proposal. In our demonstration, we trap a calcium ion together with a calcium hydride ion (CaH+) that is a convenient stand-in for more general molecular ions. We cool the two-ion crystal to its motional ground state and then drive the motional sidebands of Raman transitions in the molecular ion. A transition of the molecule is indicated by a single quantum of excitation in the secular motion of the pair. We can efficiently detect this single quantum with the calcium ion, which projects the molecule into the final state of the attempted sideband transition, leaving the molecule in a known, pure quantum state. The molecule can be coherently manipulated after the projection, and its final state read out by another quantum logic state detection. We demonstrate this by driving Rabi oscillations between rotational states. All transitions we address in the molecule are driven by a single, far off-resonant continuous-wave laser. This makes our approach applicable to control and precision measurement of a large class of molecular ions. Other QI projects in the NIST Ion Storage group will be briefly summarized. [1] P.O. Schmidt, et al. Science 309, 749 (2005) [2] D. Leibfried, New J. Phys. 14, 023029 (2012) *supported by ARO, IARPA, ONR, and the NIST Quantum Information program

11:30am - 12:00pmKenneth Rudinger, Sandia
Experimental demonstration of robust phase estimation near the Heisenberg limit

Abstract. High-fidelity gate operations are one of many requirements for full-scale quantum computation. A variety of benchmarking and tomographic protocols have been developed to aid in the characterization and improvement of these operations. In this talk, we will discuss robust phase estimation (RPE), a particular protocol that can be used to learn the phases of quantum operations to very high accuracy. Unlike many other phase estimation protocols, RPE requires no ancillae nor near-perfect state preparation or measurement. We demonstrate the first published experimental implementation of RPE on a single-qubit system (a trapped Yb\(^+\) ion), and use it to learn the phases of X and Y rotations to within \(\sim10^{-4}\) radians. This accuracy requires only 352 experimental samples per phase, and exhibits Heisenberg-like scaling. We also explore how this accuracy appears to outperform the original theoretical bounds on RPE. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04 94AL85000.

SQuInT Chief Organizer
Akimasa Miyake, Assistant Professor
amiyake@unm.edu

SQuInT Co-Organizer
Mark M. Wilde, Assistant Professor LSU
mwilde@phys.lsu.edu

SQuInT Administrator
Gloria Cordova
gjcordo1@unm.edu
505 277-1850

SQuInT Event Coordinator
Karen Jones, LSU
kjones@cct.lsu.edu

SQuInT Founder
Ivan Deutsch, Regents' Professor
ideutsch@unm.edu

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