UHFQA Quantum Analyzer

The Zurich Instruments UHFQA Quantum Analyzer is a unique tool for parallel readout of up to 10 superconducting or spin qubits with highest speed and fidelity. The UHFQA covers a frequency span of up to ±600 MHz, with nanosecond timing resolution. It features 2 signal inputs and outputs for IQ base-band operation. Thanks to its low-latency signal processing chain of matched filters, real-time matrix operations, and state discrimination, the UHFQA supports roadmaps for ambitious quantum computing projects with 100 qubits and more.

UHFQA Key Features

  • 1.8 GSa/s, ±600 MHz measurement range by single-sideband modulation
  • Parallel readout of up to 10 qubits
  • Configurable matched filters, signal conditioning, crosstalk suppression, threshold operations
  • 12-bit dual-channel input, 14-bit dual-channel AWG
  • LabOne® control software (check compatibility) and APIs for LabVIEW®, Python, C, MATLAB®, .NET

UHFQA Applications

  • Superconducting qubit quantum computing
  • Spin qubit quantum computing


For what qubit types and readout methods is the UHFQA suited?
The UHFQA is designed for readout methods based on pulsed, time-integrated measurement of a radio-frequency signal on timescales from tens of nanoseconds to a few milliseconds duration. This covers dispersive readout of superconducting qubits in a circuit QED architecture, as well as some RF reflectometry methods to read out semiconductor spin qubits.
For what qubit types and readout methods is the UHFQA not suited?
The UHFQA does not have a counter functionality that is typically required for trapped-ion qubit measurement. For these experiments, we recommend the HDAWG Arbitrary Waveform Generator, which combines multi-channel AWG functionality with pulse counter. The UHFQA is also not designed for measurement schemes based on DC voltage or current measurements, nor on methods relying on detecting electron tunneling events.
Can the UHFQA be upgraded with the same functionality as the UHFLI and UHFAWG products (such as lock-in amplifier, PID/PLL, or Boxcar Averager)?
No, the upgrade options available for the UHFLI and UHFAWG are not available for the UHFQA. However, the arbitrary waveform generator of the UHFQA is identical to the UHF-AWG Arbitrary Waveform Generator.
How can I connect the UHFQA to other Zurich Instruments products?
The UHFQA connects to the PQSC Programmable Quantum System Controller with the 32-bit DIO VHDCI interface. This enables transfer of qubit readout results to the PQSC.

The UHFQA can also connect to the HDAWG Arbitrary Waveform Generator with the 32-bit VHDCI interface. This can be useful for basic feed-forward protocols. Due to the different voltage levels (5 V of the UHFQA and 3.3 V of the HDAWG), a voltage divider is required. Please contact Zurich Instruments for further information.

Do I need the PQSC Programmable Quantum System Controller to operate the UHFQA?
No. The UHFQA can be controlled, and its measurement data obtained, with a conventional computer. The measurement data for real-time processing can be transmitted as a basic parallel TTL signal to custom digital electronics, just as well as to the PQSC.
Do I need the HDAWG Arbitrary Waveform Generator to operate the UHFQA?
No. The UHFQA can be triggered by any conventional AWG or by an internal trigger source.
What software do I need to operate the UHFQA?
The UHFQA comes with the LabOne software including APIs for Python, LabVIEW, MATLAB, C, and .NET. A Python driver for the open-source QuCoDeS measurement framework is available, however this driver is not maintained by Zurich Instruments. The Python APIs examples delivered with the software are guided by the qubit readout application and enable fast integration into other measurement frameworks.
What is the purpose of the Signal Conditioning matrix (2x2 real)?
Its purpose is to compensate for signal crosstalk and IQ mixer phase imbalance.
What is the purpose of the Rotation matrices (10 times 2x2 real)?
Their purpose is to transform the signal after the integration for each qubit such that the signal is in one signal quadrature only.
What is the purpose of the Crosstalk Suppression matrix (10x10 complex)?
Its purpose is to eliminate effects of unwanted coupling between circuit elements on the quantum computing chip, e.g., coupling from one qubit to the readout resonator of another qubit.

UHFQA Functional Diagram


UHFQA Description

Fast readout at high fidelity

The UHFQA implements a pulsed measurement to determine transmission amplitude and phase of the device
under test. Two methods are available to maximize the signal-to-noise ratio: pulse shaping and matched filtering.
Pulse shaping with the arbitrary waveform generator minimizes the ring-up and ring-down time even
for a device with slow response. The step response of the UHFQA’s digital filters can be matched to the transient response of the device by programming a 4 kSa long weight function for each filter. Compared to a simple unweighted integration, applying a properly matched filter significantly improves signal-to-noise ratio.

Scalable quantum setup

Measuring 10 qubits on a single microwave line means optimizing the cryogenic amplification chain. A configurable 10×10 matrix signal processor allows systematic suppression of crosstalk and therefore relaxed tolerances in device fabrication. In combination with the Zurich Instruments HDAWG, several UHFQA constitute a fully synchronized instrumentation layer for qubit control and readout in the quantum stack. The low-latency 32- bit DIO interface enables feed-forward of the multi-qubit
state for quantum error correction methods.

Quantum-ready software

The UHFQA is controlled by the LabOne® software with APIs for Python, LabVIEW®, MATLAB®, and .NET. An extended example library in Python enables a straightforward integration into established measurement frameworks. Thanks to the data structuring and processing functionality provided by the LabOne Data Server, the user part of the software stack remains slim and is easy to maintain.


UHFQA Specifications

Qubit measurement unit
Filter memory 4096 Sa/channel
Real-time matrix operations 1× deskew (2×2 real)
10× rotation (2×2 real)
1x crosstalk suppression (10×10 complex)
Matrix elements Range -1 to +1
Resolution <20e-6
Data logger Memory 1 MSa
Max. 217 averages
Monitoring scope memory 4096 Sa/channel, 2 channels
Monitoring scope averaging Max. 215 averages
Statistics unit Count number of logical 1 in bit pattern
Count number of transitions in bit pattern
UHF signal inputs
Frequency range DC - 600 MHz
Input impedance 50 Ω or 1 MΩ || 18 pF
Input voltage noise 4 nV/√Hz above 100 kHz
Input ranges ±10 mV to ±1.5 V
A/D conversion 12 bits, 1.8 GSa/s
Arbitrary waveform generator
Channels 2
Markers 2/channel
D/A conversion 14 bits, 1.8 GSa/s
Output ranges ±150 mV, ±1.5 V (high-impedance load)
-12.5 dBm, +7.5 dBm (50 Ω load)
Waveform memory 128 MSa/channel (main)
32 kSa/channel (cache)

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