The innovative features and capabilities of the SHFQA will be presented at a launch event on 17 November 2020. The live session will include a demo and additional details on the integration of the SHFQA into the Quantum Computing Control System (QCCS).
8.5 GHz Quantum Analyzer
- 2 or 4 readout channels, up to 64 qubits
- Operation at up to 8.5 GHz with 1 GHz analysis bandwidth and free from mixer calibration
- Real-time signal processing chain with matched filters and multi-state discrimination
- 14-bit input at 4 GSa/s, 14-bit output at 6 GSa/s
- Controlled through LabOne®, the LabOne QCCS control software, or APIs for Python, C, MATLAB®, LabVIEW™ and .NET
The Zurich Instruments SHFQA Quantum Analyzer integrates in a single instrument a full real-time readout setup for up to 64 superconducting and spin qubits. The SHFQA operates in a frequency range from 0.5 to 8.5 GHz with a clean analysis bandwidth of 1 GHz and without the need for mixer calibration.
Each of its 2 or 4 readout channels can analyze up to 16 qubits, 8 qutrits or 5 ququads. For the 2-channel instrument, this performance requires the SHFQA-16W option.
The SHFQA enables multi-state discrimination with an optimal signal-to-noise ratio and minimal latency thanks to its advanced sequencer and the low-latency signal processing chain with matched filters and result correlation. The data can be transmitted in real time to other instruments for active qubit reset or global error correction protocols. Controlled through the LabOne software suite, which comprises the user interface, several APIs and the LabOne QCCS control software, the SHFQA supports quantum computing projects with sizes ranging from a few to several hundreds of qubits.
Quantum computing applications
- Frequency-multiplexed readout
- Single-shot dispersive readout
- Resonator spectroscopy and characterization
- Real-time, low-latency and global feedback for error correction
Supported qubit types
- Superconducting qubits
- Spin qubit/superconducting resonator hybrids
- Qubits, qutrits and ququads
- Amplifier noise characterization
- External IQ mixer calibration
The SHFQA performs pulsed measurements to determine the transmission amplitude and phase of the device under test. There are two methods to maximize the signal-to-noise ratio (SNR): pulse shaping and matched filtering. Pulse shaping with an arbitrary waveform generator minimizes the ring-up and ring-down time even for a device with a slow response.
The step response of the SHFQA'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 the SNR. In addition, the real-time analysis chain makes it possible to discriminate up to 4 states per qubit and to correlate the qubit results.
Scalable quantum setup
Measuring 16 qubits or 8 qutrits on a single microwave line means optimizing the cryogenic amplification chain. The freely configurable integration weights reduce qubit crosstalk and, consequently, relax tolerances in device fabrication. The memory blocks (up to 16) in the arbitrary waveform generator enable the readout and trigger readout of the qubits, qutrits or ququads in a time-staggered manner. The possibility to choose 2 or 4 readout channels, and to extend the number of integration weights from 8 to 16 for the 2-channel version, means that users can tailor the instrument to their specific system requirements.
For maximum integration, the SHFQA can be efficiently interfaced with other instruments too. For example, the low-latency 32-bit DIO VHDCI interface enables feed-forward of the multi-qubit state to a few HDAWGs for fast active qubit reset. For systems with larger qubit counts, several SHFQAs, HDAWGs, HDIQs and a PQSC can be combined to form a scalable Quantum Computing Control System (QCCS). The Zurich Instruments ZSync interface links the SHFQA to all other instruments in the QCCS through the central PQSC, which is especially important for global error correction protocols.
Clean and calibration-free frequency conversion to 8.5 GHz
When reading out multiple qubits through resonators coupled to the same readout line, even small spurs can lead to a confusing or smaller readout signal if they are sub-optimally located. As the SHFQA's double superheterodyne up- and down-conversion scheme up to 8.5 GHz relies on filtering rather than on interference, it performs over a wider frequency band and with better linearity than standard IQ-mixer-based conversion. As a result, even a single tone can be generated with fewer spurs and straight out of the box. Importantly, the performance is stable and does not require tedious mixer calibrations. This approach, combined with an analysis bandwidth of 1 GHz, affords more flexibility when designing the resonator frequencies for frequency-multiplexed qubit readout; it also simplifies greatly the system's tune-up and maintenance.
Quantum system control software
As part of our Quantum Computing Control System, the SHFQA can be fully integrated into new or existing setups using the LabOne QCCS control software. As a standalone unit, it can be controlled with LabOne and its APIs for Python, C, MATLAB®, LabVIEW™ and .NET. An extended example library facilitates integration into established measurement frameworks. Thanks to the data structuring and processing functionality offered by the LabOne Data Server, the user portion of the software stack remains simple and easy to maintain.
|Number of RF inputs||2 or 4|
|Frequency range||0.5 - 8.5 GHz|
|Signal bandwidth||1 GHz|
|Input impedance||50 Ohm|
|Input voltage noise||4 nV/√Hz (@ 3 GHz)|
|Input ranges (dBm)||-40 to 10 dBm (calib.)|
|A/D conversion||14-bit, 4 GSa/s|
Qubit measurement unit
|Matched filters||16 complex filters/readout channel for 4-channel instrument
8 complex filters/readout channel for 2-channel instrument (extended to 16 with SHFQA-16W option)
4096 memory samples per filter and quadrature
|Multistate discrimination||Up to 4 discriminators|
|Data logger||Memory: 220 samples, max. 217 averages|
|Monitor scope||Memory: 219 complex samples when monitoring 1 channel, 218 samples when monitoring 2 channels, 217 samples when monitoring 3 to 4 channels
Averaging: Max. 216 averages
|Number of RF outputs||2 or 4|
|Frequency range||0.5 - 8.5 GHz|
|Signal bandwidth||1.0 GHz|
|Output impedance||50 Ohm|
|Output voltage noise||14.1 nV/√Hz @ 6 GHz|
|Output ranges (dBm)||-30 dBm to +10 dBm (calib.)|
|D/A conversion||14-bit, 6 GSa/s|
Readout pulse generator
|Number of waveform generators||1 per readout channel (2 or 4 in total)|
|Sequencing capability||Advanced sequencing (loop, branching), command table, advanced trigger control (staggered readout capability)|
|For 4-channel instrument: 64 kSa total memory, configurable in 16x4 kSa, 8x8 kSa, or 1x64 kSa
For 2-channel instrument: 32 kSa total memory, configurable in 8x4 kSa, or 1x32 kSa
For 2-channel instrument (with SHFQA-16W option): 64 kSa total memory, configurable in 16x4 kSa, 8x8 kSa, or 1x64 kSa
|Number of readout channels||2 or 4|
|Dimensions||449 x 460 x 145 mm (19" rack)
17.6 x 18.1 x 5.7 inch
|Weight||15 kg (33 lb)|
|Power supply||AC: 100-240 V, 50/60 Hz|
|Connectors||SMA on front and back panel for trigger, signals and external clock
LAN/Ethernet, 1 Gbit/s
1 All memory blocks are freely configurable and triggerable.
The 4-channel version and fully featured (i.e., including the SHFQA-16W-option) 2-channel version of the SHFQA allow you to optimally detect 16 qubits, 8 qutrits or 5 ququad states per readout channel. The base version of the 2-channel SHFQA allows you to detect 8 qubits, 4 qutrits or 2 ququads.
The SHFQA is best suited for readout schemes that modify a probe signal in the microwave regime: for example, the schemes commonly used for reading out superconducting circuits or hybrid superconducting/spin-qubit systems.
The SHFQA is not suitable for readout schemes that are based on photon counting, because it does not include counter functionality, or for schemes requiring operation below 0.5 GHz.
With every release of our LabOne software, we provide new tools and features. For example, fast resonator spectroscopy helps you measure and characterize your readout line in the shortest time. We also offer a library of Python notebooks and tutorials to help you set up and control your SHFQA as quickly as possible.
No, you don't. Both RF input and output of the SHFQA are designed to be directly connected to the qubit readout line of the cryostat as long as the readout frequencies are within the measurement band of 0.5-8.5 GHz and the signal has been pre-amplified at the cold state, e.g., by a HEMT amplifier.
A strong pump tone may cause the pre-amplifiers before the first mixer stage to become non-linear, leading to a potentially reduced SNR or more spurs in the readout spectrum. You have two options to overcome this effect:
- Do not use the pre-amplifiers. In this case, the filter after the first mixer stage might be able to filter out the pump tone signal. Of course, you need to make sure that the signal level is still in a suitable range for the SHFQA to be detected.
- Add a pump tone cancellation circuit between the SHFQA and the cryostat.
The SHFQA comes with the LabOne software and its APIs for Python, C, MATLAB®, LabVIEW™ and .NET. The examples of Python APIs included with the software are guided by the qubit readout application and enable fast integration into other measurement frameworks. The LabOne software and APIs are produced by Zurich Instruments and upgraded on a regular basis, providing you with new instrument features and functionalities.
The SHFQA was conceived to be interfaced with the PQSC through the Zurich Instruments ZSync link that provides both system-wide clock synchronization and data distribution. Furthermore, it also provides a 32-bit DIO VHDCI interface that can be used to directly connect the SHFQA to other instruments of the QCCS for fast feedback, such as the HDAWG, or to third-party instruments.
No, you don't. The SHFQA 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 through the 32-bit DIO VHDCI. However, for optimal synchronization with other instruments of the QCCS, we strongly recommend that you use a PQSC.
No, because the SHFQA can be used as a standalone system: it offers everything that is needed to replace 4 full room-temperature multi-qubit readout systems, including frequency conversion up to 8.5 GHz. It can be triggered through an internal trigger source or any conventional TTL-signal generator.
Yes: each readout channel of the SHFQA is a drop-in replacement of one UHFQA.
Yes, but we strongly recommend to use only one type of instrument in a given setup.