Rapid optimization of working parameters of microwave-driven multi-level qubits for minimal gate leakage

We propose an effective method to optimize the working parameters (WPs) of microwave-driven quantum logical gates implemented with multi-level physical qubits. We show that by treating transitions between each pair of levels independently, intrinsic gate errors due primarily to population leakage to undesired states can be estimated accurately from spectroscopic properties of the qubits and minimized by choosing appropriate WPs. The validity and efficiency of the approach are demonstrated by applying it to optimize the WPs of two coupled rf SQUID flux qubits for controlled-NOT (CNOT) operation. The result of this independent transition approximation (ITA) is in good agreement with that of dynamic method (DM). Furthermore, the ratio of the speed of ITA to that of DM scales exponentially as 2^n when the number of qubits n increases.Comment: 4pages, 3 figure

Periportal Capsulotomy: A Technique for Limited Violation of the Hip Capsule During Arthroscopy for Femoroacetabular Impingement.

Hip arthroscopy has become the standard treatment for symptomatic femoroacetabular impingement as patients have shown good outcomes and high satisfaction with this intervention. However, capsular management to gain access for intra-articular procedures remains greatly debated. Capsular closure is advocated particularly in the setting of interportal or T-capsulotomy to avoid complications of instability or nonhealing capsule. We introduce a technique for capsular management through a limited periportal capsulotomy during arthroscopic treatment of femoroacetabular impingement. In using dilation of the anterolateral and mid-anterior portals without completion of a full interportal capsulotomy, the stabilizing iliofemoral ligament is preserved. We have found that periportal capsulotomy provides safe and sufficient access to the hip joint without necessitating capsular closure

Coherent Imaging Spectroscopy of a Quantum Many-Body Spin System

Quantum simulators, in which well controlled quantum systems are used to reproduce the dynamics of less understood ones, have the potential to explore physics that is inaccessible to modeling with classical computers. However, checking the results of such simulations will also become classically intractable as system sizes increase. In this work, we introduce and implement a coherent imaging spectroscopic technique to validate a quantum simulation, much as magnetic resonance imaging exposes structure in condensed matter. We use this method to determine the energy levels and interaction strengths of a fully-connected quantum many-body system. Additionally, we directly measure the size of the critical energy gap near a quantum phase transition. We expect this general technique to become an important verification tool for quantum simulators once experiments advance beyond proof-of-principle demonstrations and exceed the resources of conventional computers

Quantum harmonic oscillator state synthesis and analysis

Experiments are described in which a single, harmonically bound, beryllium ion in a Paul trap is put into Fock, thermal, coherent, squeezed, and Schroedinger cat states. Experimental determinations of the density matrix and the Wigner function are described. A simple calculation of the decoherence of a superposition of coherent states due to an external electric field is given.Comment: 13 pages, LaTeX2e, special style file spie.sty included, 11 eps figures included using epsfig, graphicx, subfigure, floatflt macros. To appear in Proc. Conf. on Atom Optics, San Jose, CA, Feb. 1997, edited by M. G. Prentiss and W. D. Phillips, SPIE Proc. # 299

Quantum information processing with atoms and photons

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/62643/1/416238a.pd