G. Ott

The STAR Silicon Vertex Tracker: A Large Area Silicon Drift Detector

Abstract The Solenoidal Tracker At RHIC-Silicon Vertex Tracker (STAR-SVT) is a three barrel microvertex detector based upon silicon drift detector technology. As designed for the STAR-SVT, silicon drift detectors (SDDs) are capable of providing unambiguous two-dimensional hit position measurements with resolutions on the order of 20 μm in each coordinate. Achievement of such resolutions, particularly in the drift direction coordinate, depends upon certain characteristics of silicon and drift detector geometry that are uniquely critical for silicon drift detectors hit measurements. Here we describe features of the design of the STAR-SVT SDDs and the front-end electronics that are motivated by such characteristics.

First steps in the silicon vertex trigger upgrade at CDF

The silicon vertex trigger (SVT) in the CDF experiment at Fermilab performs fast and precise track finding and fitting at the second trigger level and has been a crucial element in data acquisition for Run II physics. However as luminosity rises, multiple interactions increase the complexity of events and thus the SVT processing time, reducing the amount of data CDF can record. The SVT upgrade aims to increase the SVT processing power to restore at high luminosity the original CDF DAQ capability. We describe the first steps in the SVT upgrade, consisting of a new associative memory with 4 times the number of patterns, and a new track fitter to take advantage of these patterns. We describe the system, its tests and its performance

Studies of dynamics of electron clouds in STAR silicon drift detectors

Abstract The dynamics of electrons generated in silicon drift detectors was studied using an IR LED. Electrons were generated at different drift distances. In this way, the evolution of the cloud as a function of drift time was measured. Two methods were used to measure the cloud size. The method of cumulative functions was used to extract the electron cloud profiles. Another method obtains the cloud width from measurements of the charge collected on a single anode as a function of coordinate of the light spot. The evolution of the electron cloud width with drift time is compared with theoretical calculations. Experimental results agreed with theoretical expectations.

Electron injection in semiconductor drift detectors

Abstract We report on the injection of electrons from surface structures of Silicon Drift Detectors into the bulk of the detector for calibration purposes. Also, with these injector structures, detection of magnetic field components perpendicular to the detector’s surface is possible. Implanted line and dot injectors along with MOS injectors are discussed. Studies of lateral uniformity of injection, biasing of injectors to facilitate injection and dot injection are discussed.

Classical emulation of a quantum computer

This paper describes a novel approach to emulate a universal quantum computer with a wholly classical system, one that uses a signal of bounded duration and amplitude to represent an arbitrary quantum state. The signal may be of any modality (e.g. acoustic, electromagnetic, etc.) but this paper will focus on electronic signals. Individual qubits are represented by in-phase and quadrature sinusoidal signals, while unitary gate operations are performed using simple analog electronic circuit devices. In this manner, the Hilbert space structure of a multi-qubit quantum state, as well as a universal set of gate operations, may be fully emulated classically. Results from a programmable prototype system are presented and discussed.

Signal-based classical emulation of a universal quantum computer

In this paper we present a novel approach to emulating a universal quantum computer with a classical system, one that uses a signal of bounded duration and amplitude to represent an arbitrary quantum state. The signal may be of any modality (e.g., acoustic, electromagnetic, etc), but we focus our discussion here on electronic signals. Unitary gate operations are performed using analog electronic circuit devices, such as four-quadrant multipliers, operational amplifiers, and analog filters, although non-unitary operations may be performed as well. In this manner, the Hilbert space structure of the quantum state, as well as a universal set of gate operations, may be fully emulated classically. The required bandwidth scales exponentially with the number of qubits, however, thereby limiting the scalability of the approach, but the intrinsic parallelism, ease of construction, and classical robustness to decoherence may nevertheless lead to capabilities and efficiencies rivaling that of current high performance computers.

Electron identification using a synchrotron radiation detector

Abstract A xenon filled multiwire proportional chamber was used to detect synchrotron radiation from high energy electrons traversing the field of a standard spectrometer magnet. Signals from the chamber were used to achieve an electron trigger with a pion rejection of ∼ 17 and an average electron detection efficiency of 81%. Off-line analysis of the chamber signals increased the pion rejection to 59 with an electron efficiency of 77%.

Two dimensional studies of dynamics of electron clouds in silicon drift detectors

The dynamics of electrons generated in silicon drift detectors is studied using an IR LED. Electrons were generated at different drift distances. In this way the evolution of the cloud in anode and drift directions as a function of drift time was measured. For the anode direction the method of cumulative functions was used to extract the electron cloud profiles. The cloud width was obtained also from measurements of the charge collected on a single anode as a function of the coordinate of the light spot. We present the first report of the experimental measurements of the cloud width in the drift direction extracted from signal waveforms. The evolution of the electron cloud width with drift time is compared with theoretical calculations. Theoretical expectations agree with our experimental results.

Quantum Decoherence Emulated in a Classical Device

We demonstrate that a classical emulation of quantum gate operations, here represented by an actual analog electronic device, can be modeled accurately as a quantum operation in terms of a universal set of Pauli operators. This observation raises the possibility that quantum error correction methods may be applied to classical systems to improve fault tolerance.

Using quantum emulation for advanced computation

A novel concept for advanced computation is considered using an analog electronic emulation of a gate-based quantum computer. We discuss a general classes of problems for which such a device is well suited, examine the expected computational speedup versus bandwidth, and describe the measured performance of a small-scale hardware prototype.