Quantum & Physics

In this article, we show experimental results from using the Tabor Proteus AWT when directly characterizing a super conducting Qubit.

Quantum physics is transforming the technology landscape and most innovative companies are continuously researching on how they can use it to build products that address challenges that classical systems cannot. In this article we will discuss how researchers are using arbitrary waveform generators / Transceivers to simulate real-world conditions when performing quantum experiments.

This white paper introduces the Effective Number of Bits (ENoB) concept and its impact on the real performance of AWGs in different applications. The ENoB specification is made of multiple parameters and the importance of each greatly depends on the signal being generated and the way it will be applied to the system under test.

The IEEE 1658-2011 standard covers some test methodologies to obtain the SINAD parameter, so the ENoB specification can be directly calculated. One of the methods is based on acquiring the test signal (a sinewave) being generated by the DAC with a suitable ADC. Examining the signal in the frequency domain or breaking the signal into its constituent parts using an FFT (Fast Fourier Transform) allows us to identify and evaluate the signal.

We have learned so far that the ENOB summarizes the impact of multiple linear and non-linear distortions and noise sources with respect to the quality of the output signal of an AWG. However, it does not provide all the information required to assess the performance of an AWG for different types of signal conditions. Using the case of high-speed digital, an AWG can generate a multi-level PAM (Pulse-Amplitude Modulation) signal by defining the level corresponding to each successive symbol

Some AWGs and DACs use samples with a higher resolution than the DAC itself. The Tabor Proteus uses 16-bit samples while the DAC core is 14-bit. The advantage of this method is that SNR will be minimally affected by any calculations for any intermediate signal processing. For example, a common processing stage is an x/sin(x) digital filter that is usually applied before data conversion to flatten the frequency response.

Nuclear Magnetic Resonance (NMR) Spectroscopy is a technique used for determining the structure of organic compounds. Some nuclei possess a magnetic moment. In a strong magnetic field, the magnetic moment of each nucleus will align with the magnetic field of the magnet. If you apply resonant RF energy it will cause the nuclei to jump to a higher-energy state and the nuclei magnetic moments will rotate or process

In this article, we’ll review the Quantum setup architecture, in regards to arbitrary waveform generators, and the fundamental role they have in the process of controlling quantum bits, qubit measurement, and analysis.

We will review and explain the fundamentals of wave propagation, impendence matching and transmission, passive frequency translation, and how the properties of nonlinear frequency summation devices such as mixers - can help modify the signals' frequency. We’ll cover Modulation and the process of encoding information on to generated frequency – and we will look at AM and Phase Modulation and how they are combined in a vector modulator. We will look at both analog and digital implementations of modulation, and Signal Analysis.

10 Tips for using an Arbitrary Waveform Generator (AWG) in Quantum Experiment control and measurement applications.

New trends in RF/µW signal generation and acquisition and real-time closed-loop control for classical to quantum computing interfacing. The Classical/Quantum Interface can be implemented by the Proteus AWT (Arbitrary Waveform Transceiver). This article will show how the Proteus AWT can be used to control multiple Qubits in an operational Quantum Computing system.

Complex and accurate modulation of RF signals implies the quadrature modulation of some carrier with complex (I/Q) baseband signals. AWGs have been always used to generate these baseband signals to be applied to external quadrature modulators. A new generation of high-speed AWGs can avoid external modulators by using a combination of digital processing techniques with a high-enough sampling rate to directly generate modulated RF signals in the microwave region.

Real-World high-speed arbitrary waveform generators and digitizers can't implement a perfect flat frequency response with a linear phase (fixed delay) behavior over the full bandwidth. It is virtually impossible to reproduce exactly the same response for all the instruments and even for all the different channels in the same device. Some applications can cope with such limitations. Others, such as qubit control or wireless test, can't. The solutions are calibration and corrections.

The AWT concept implemented by the Proteus platform is not just a convenient combination of an AWG and a digitizer in a single device, it is a full-fledged closed-loop processing and control solution. Each basic Proteus cell incorporates a powerful FPGA from Xilinx, the UltraScale KU-060 model, tightly connected to all the analog and digital input/output blocks. The current implementation allows for the future incorporation of even more powerful and faster FPGAs.

AWGs and Digitizers can be powerful RF signal generation and acquisition tools. This paper shows how high-performance AWTs (Arbitrary Waveform Transceivers) can be used as simple but powerful RF T&M gear. The Tabor Proteus AWT, with generation and acquisition capabilities beyond 8GHz, can be applied to test systems for the microwave region using techniques as full digital up-conversion/IQ modulation and down-conversion/IQ demodulation, multi-Nyquist zone operation and high RF performance.

Entangled qubits can also be used for secure communications. When two qubits are entangled, the measurement of the first qubit creates the opposite condition in the other, regardless of their positions in time and space - the qubits continue to affect each other no matter the distance in miles or even in time

In quantum computing, a qubit is a unit of quantum information. A qubit is a two-state quantum-mechanical system and is the quantum analog of the classical bit. In a classical system, a bit would have to be in one state or the other. However, quantum mechanics allows the qubit to be in a superposition of both states at the same time.

There are various types of experiments performed in the field of controlling quantum bits and qubit measurement, as one experiment can be significantly different from another. Therefore, we will explain in general a common setup for a superconducting qubit experiment. We will focus on the Arbitrary Waveform Generators' part of the experiment setup.