SHFQC 8.5 GHz Qubit Controller

Key Features

2, 4, or 6 signal generator channels
1 quantum analyzer channel for qubits, qutrits or ququads
Operation at up to 8.5 GHz with 1 GHz analysis bandwidth and free of mixer calibration. Contact us if frequencies >8.5 GHz are required.
Low phase noise, low spurious tones, high output power for fast high-fidelity gates
Real-time signal processing chain with matched filters and multi-state discrimination
Instrument-internal feedback of 350 ns
Controlled through LabOne^®, the LabOne QCCS software, or the APIs for Python

Variants

Price

Documents

The SHFQC Qubit Controller can control, read out and provide fast feedback on up to 6 superconducting qubits. It integrates the functionality of the SHFQA Quantum Analyzer, the SHFSG Signal Generator and more in a single instrument. With integrated microwave generation, a trigger distribution unit and the ultrafast feedback of 350 ns between all channels, simple microwave connections between the SHFQC and a cryostat are sufficient to start advanced qubit measurements. To provide flexibility for systems with a small number of qubits, the SHFQC comes in three possible configurations, in which either 2, 4, or 6 of the signal generator channels are enabled. For the 2- and 4-channel configurations, additional signal generator channels can be enabled in the field. As a result, the setup is fully software-controlled and can be reconfigured as needed to match the experimental requirements.

SHFQC Qubit Controller

Each control channel of the SHFQC has its own powerful sequencer for creating phase- and timing-programmable waveforms, so that a single SHFQC can control or couple qubits with pulses from DC to 8.5 GHz, and react at any time on measurements from the readout channel. With the SHFQC-16W upgrade option, the readout channel's freely configurable integration weights and readout-pulse memories are doubled from 8 to 16. This provides more flexibility in configuring the readout, e.g. by enabling full real-time control and readout of 6 qutrits.

Advanced features such as a real-time oscilloscope, fast spectroscopy, and the pulse-level sequencing capability allow users to further speed up their system tune-up and measurements.

The SHFQC integrates into the Zurich Instruments Quantum Computing Control System (QCCS) and is intuitively operated through the LabOne QCCS Software. This enables a seamless combination with other instruments such as the HDAWG for fast flux or gate voltage signals up to 750 MHz. Within a larger QCCS, the SHFQC enables access to fast local and global feedback as well as to error correction protocols for 100 qubits and beyond.

Channel configurations for the SHFQC Qubit Controller

The SHFQC comes with three possible configurations: either 2, 4, or 6 of the signal generator channels can be enabled. Additional channels can be enabled in the field. To ask about changing the configuration of your SHFQC, contact us at info@zhinst.com.

Configuration	Number of enabled signal generator channels	Number of additional channels that can be enabled later	Number of quantum analyzer channels
SHFQC2	2	2 or 4	1
SHFQC4	4	2	1
SHFQC6	6	0	1

High-fidelity qubit manipulation and readout

Operating over a range that extends up to 8.5 GHz, the SHFQC's double superheterodyne up- and down-conversion scheme relies on filtering rather than on interference, so that it performs over a wider frequency band and with better linearity than standard IQ-mixer-based conversion approaches. This capability is combined with the performance of synthesizers specifically designed for high-fidelity qubit control and readout, offering low phase noise and low timing jitter across the whole output frequency range. As a result, the SHFQC generates spurious-free, stable signals within an instantaneous bandwidth of 1 GHz and without requiring its users to spend time on mixer calibration or system maintenance.

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. The superheterodyne scheme of the SHFQC affords more flexibility on the design of resonator frequencies for frequency-multiplexed qubit readout. Furthermore, the combination with a linear amplification chain allows users to drive all single- and multi-qubit gates within short time intervals and free of distortion. The integrated frequency conversion offered by the SHFQC ensures that qubit control and readout operations realize the full potential of a quantum processor in terms of fidelity.

Efficient workflow and resource handling

The SHFQC's Signal Generator and Quantum Analyzer channels support minimal use of waveform data even when complex signals are required. Users provide the desired signals in the form of pulse descriptions to program the SHFQC in the most memory-efficient manner. Even for many-qubit systems that rely on multiple SHFQCs, this approach ensures that complex tune-up and calibration routines are completed within a minimum of instrument communication time. For example, the support of loops and conditional branching points enables the implementation of active reset in 350 ns as well as more complex quantum error-correction codes; real-time phase and frequency updates make it possible to implement virtual Z gates. With up to 98 kSa waveform memory per channel, the ability to handle up to 32k sequence instructions, and a sampling rate of 2 GSa/s, the SHFQC provides customizable multi-channel AWG signals for qubit control and readout.

Fast readout with high fidelity

The SHFQC 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 readout pulse generator minimizes the ring-up and ring-down time even for a device with a slow response.

The step response of the SHFQC's digital filters can be matched to the transient response of the device by programming a 4-kSa-long (2-us-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 can discriminate up to 4 states per qubit.

Scalable system approach

By design, the SHFQC supports a processor consisting of up to 6 fixed-frequency qubits, qutrits or 5 ququads. To optimally support other qubit types, or for integration into a scalable quantum system, the SHFQC 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 or real-time flux-pulse control.

For systems with larger qubit counts, several SHFQCs, SHFSGs, SHFQAs and HDAWGs can be combined to form a scalable Quantum Computing Control System (QCCS). To this end, the Zurich Instruments ZSync interface links the SHFQCs and all other instruments to each other through the central PQSC Programmable Quantum System Controller. The LabOne QCCS Software optimizes inter-instrument communication, thus simplifying protocol execution.

Up to 18 instruments can be synchronized through a PQSC, leading to coordinated readout and control of up to 128 qubits using SHFSGs and SHFQAs, or of up to 108 qubits including ultrafast feedback using only the SHFQCs. All instruments that are synchronized through a PQSC can be programmed with the LabOne QCCS Software or the APIs for Python, so that users decide how they wish to incorporate them into new or existing setups.

Quantum system control software

As part of our QCCS, the SHFQC can be fully integrated into new or existing setups using the LabOne QCCS Software. As a standalone unit, it can also be efficiently controlled with LabOne and its Python APIs. An extended example library facilitates intuitive 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.

General

Number of control channels	Up to 6 signal generator channels
Number of readout channels	1 quantum analyzer channel (1 input and 1 output channel)
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 32-bit DIO 2 ZSync LAN/Ethernet, 1 Gbit/s USB 3.0 Maintenance USB

Signal generator signal outputs

Number of RF outputs	6, of which 2, 4, or 6 can be enabled
Frequency range	DC - 8.5 GHz
Signal bandwidth	> 1 GHz
Output ranges (dBm)	-30 dBm to 10 dBm
Output impedance	50 Ohm
Number of synthesizers	3 (pairs of channels share a synthesizer)
D/A conversion	14-bit, 6 GSa/s (after internal 3x interpolation)
Output voltage noise density	-135 dBm/Hz (1 GHz, 10 dBm, offset > 200 kHz) -140 dBm/Hz (4 GHz, 10 dBm, offset > 200 kHz) -144 dBm/Hz (6 GHz, 10 dBm, offset > 200 kHz) -144 dBm/Hz (8 GHz, 10 dBm, offset > 200 kHz)
Output phase noise	-90 dBc/Hz (6 GHz, carrier offset 1 kHz) -98 dBc/Hz (6 GHz, carrier offset 10 kHz) -100 dBc/Hz (6 GHz, carrier offset 100 kHz)
Output level accuracy	±(1 dBm of setting)
Spurious-free dynamic range (excl. harmonics)	74 dBc (1 GHz, 0 dBm) 66 dBc (4 GHz, 0 dBm) 60 dBc (6 GHz, 0 dBm) 65 dBc (8 GHz, 0 dBm)
Output worst harmonic component	-40 dBc (1 GHz, 10 dBm) -40 dBc (4 GHz, 10 dBm) -38 dBc (6 GHz, 10 dBm) -36 dBc (8 GHz, 10 dBm)

Waveform generation

AWG cores	1 per channel
Waveform vertical resolution	14-bit analog + 2-bit marker
Waveform memory	98 kSa per channel
Sequence length	32k instructions per AWG core
AWG sampling rate	2 GSa/s
Minimum waveform length	32 Sa

Quantum analyzer signal outputs

Number of RF outputs	1
Frequency range	0.5 - 8.5 GHz
Signal bandwidth	> 1 GHz
Output ranges (dBm)	-30 dBm to 10 dBm
Output voltage noise	14.1 nV/sqrt(Hz) (@ 6 GHz)
Output impedance	50 Ohm
Number of synthesizers	1 (shared with input channel)
D/A conversion	14-bit, 6 GSa/s (after internal 3x interpolation)
Output voltage noise density	-135 dBm/Hz (1 GHz, 10 dBm, offset > 200 kHz) -140 dBm/Hz (4 GHz, 10 dBm, offset > 200 kHz) -144 dBm/Hz (6 GHz, 10 dBm, offset > 200 kHz) -144 dBm/Hz (8 GHz, 10 dBm, offset > 200 kHz)
Output phase noise	-90 dBc/Hz (6 GHz, carrier offset 1 kHz) -98 dBc/Hz (6 GHz, carrier offset 10 kHz) -100 dBc/Hz (6 GHz, carrier offset 100 kHz)
Output level accuracy	±(1 dBm of setting)
Spurious-free dynamic range (excl. harmonics)	74 dBc (1 GHz, 0 dBm) 66 dBc (4 GHz, 0 dBm) 60 dBc (6 GHz, 0 dBm) 65 dBc (8 GHz, 0 dBm)
Output worst harmonic component	-40 dBc (1 GHz, 10 dBm) -40 dBc (4 GHz, 10 dBm) -38 dBc (6 GHz, 10 dBm) -36 dBc (8 GHz, 10 dBm)

Readout pulse generator

Number of readout pulse generator	1
Sequencing capability	Advanced sequencing (loop, branching), command table, advanced trigger control, staggered readout
Waveform memory blocks¹	32 kSa total memory in 8 blocks or 64 kSa total memory per channel in 16 blocks (with SHFQC-16W option)
Oscillators	1 (accessible in spectroscopy mode)

Quantum analyzer signal inputs

Number of RF inputs	1
Frequency range	0.5 - 8.5 GHz
Signal bandwidth	> 1 GHz
Output impedance	50 Ohm
Number of synthesizers	1 (shared with output channel)
Input voltage noise	1.1 nV/√Hz (@ 3 GHz)
Input ranges (dBm)	-50 dBm to 10 dBm (calib.)
A/D conversion	14-bit, 4 GSa/s

Qubit measurement unit

Matched filters	32 kSa total memory per channel in 8 blocks¹ or 64 kSa total memory per channel in 16 blocks¹ (with SHFQC-16W option)
Multistate discrimination	Up to 4 discriminators
Feedback latency	350 ns (last sample in to first sample out)
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

Markers and triggers

Marker outputs	1 per input/output channel, SMA on front panel
Marker output voltages	0 V (low), 3.3 V (high)
Marker output impedance	50 Ohm
Marker output rise time	300 ps (20% to 80%)
Trigger inputs	1 per input/output channel, SMA on front panel
Trigger input impedance	50 Ohm / 1 kOhm

¹ All memory blocks are freely configurable and triggerable. One block corresponds to 4096 complex-valued samples.

General

Call us on +41 44 515 0410 or send us an email with your contact details and preferred time slot. We will be happy to schedule an online demo to discuss your requirements and see whether there is a match with the SHFQC's capabilities.
All users receive support from Zurich Instruments independently of where the purchase took place. Local sales partners, where available, also provide first-level support in the local language. For extended support, instrument calibration or service, please check our Support page.

Instrument Functionality

The SHFQC is best suited for qubits and other systems that can be controlled with microwave signals at up to 8.5 GHz – for example, gate operations and multiplexed readout on superconducting circuits or hybrid superconducting/spin qubit systems.

The SHFQC is not suitable for readout schemes that are based on photon counting, given that it does not include counter functionality, or for readout schemes requiring operation below 0.5 GHz.
No, the SHFQC always comes with 1 quantum analyzer (readout) channel and 6 signal generator (control) channels. Depending on the configuration chosen, 2, 4, or 6 of the signal generator channels can be enabled. Additional channels can be enabled in the field.
The SHFQC's 6 signal generator (control) and 1 quantum analyzer (readout) lines enable control of up to 6 superconducting qubits. In combination with other instruments, such as the Zurich Instruments HDAWG or the SHFSG, more qubits can be manipulated and read out.

Signal Generator Functionality

The SHFQC's signal generator channels readily support modulation of the in-phase and quadrature components of the internal oscillator by a dual-channel waveform signal. Based on this functionality, AM, FM, PM and DSB can be performed. The SHFQC does not support modulation by an external source though.
Sometimes yes. Each signal generator (control) channel of the SHFQC is a specialized signal generator that covers many of the capabilities of a system comprising HDAWG and HDIQ instruments. A single channel thus replaces 2 HDAWGs and 1 HDIQ channel while providing additional functionality and performance in the microwave regime. For operation close to DC - for example, with flux pulses - an HDAWG channel is often the better alternative because of its higher output power, pre-compensation functionality and larger waveform memory.

Quantum Analyzer Functionality

The SHFQC allows you to read out 8 qubits, 4 qutrits or 2 ququads in parallel; this can be extended up to 16 qubits, 8 qutrits or 5 ququads with the SHFQC-16W option.
Yes, the readout channel of the SHFQC is a drop-in replacement of a UHFQA with added functionality.

Hardware

No. All RF input and outputs of the SHFQC are designed to be directly connected to the corresponding control and readout lines of the cryostat. For a control channel this means that operation frequencies need to be within the bandwidth of DC - 8.5 GHz, for the readout channels between 0.5 GHz and 8.5 GHz. This is possible thanks to the superheterodyne frequency conversion scheme of the SHFQC, designed to bring stability and simplicity to qubit setups.
Most likely not. The SHFQC can supply up to 10 dBm of output power, which allows for very short (5 ns) gates with superconducting transmon qubits and is typically much more than what is needed for readout. At the lowest input range setting of the readout channel, -50 dBm are mapped to the full dynamic range of the ADC with minimal added noise: this means that the readout signal needs only pre-amplification at the cold state, e.g. with a HEMT amplifier.
Each channel has a trigger input on the front panel. A single sequence program can incorporate several trigger inputs and can use the state of a trigger as an input for sequence branching.
The SHFQC has 1 marker per control channel (6 in total for the 6-channel configuration) and 2 trigger outputs for the readout channel, located on the front panel. Using any of the markers/trigger outputs does not reduce the 14-bit resolution of the output.
A strong pump tone may cause the pre-amplifiers before the first mixer stage to become non-linear, leading to a potentially reduced signal-to-noise ratio 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 SHFQC to be detected.
- Add a pump-tone cancellation circuit between the SHFQC and the cryostat.

Software

Yes: this instrument is operated from a computer connected via USB 3.0 or 1 GbE. The computer uploads waveform and sequence data to the SHFQC and downloads averaged experimental results. Once the SHFQC is started, it generates its signals and acquires its data autonomously and does not strictly depend on the computer anymore.
The LabOne software is freely available from our Download Center, and it comes with a single-click function for updating the instrument firmware. The SHFQC can also be controlled with freely included APIs for Python. The examples of Python APIs included with the software are tailored towards qubit manipulation and enable fast integration into other measurement frameworks too. The LabOne software and APIs are produced by Zurich Instruments and upgraded on a regular basis, providing you with new features and functionalities on the instrument.
If you rely on custom Python code, the integration is straightforward with the LabOne APIs. Additionally, LabOne helps you to find the right API command for a given instrument setting thanks to its command log feature. Additionally, the LabOne QCCS Software operates either as a standalone control software or can be integrated into most existing frameworks and control frameworks.
With every release of our LabOne software, we provide new tools and instrument functionality. For example, fast resonator spectroscopy helps you measure and characterize your readout line in a minimal amount of time; the command table allows to minimize system down-time. We also offer a library of Python notebooks and tutorials that help you setup and control your SHFQC as quickly as possible.

System Integration

The SHFQC is intended to be interfaced with the PQSC through the Zurich Instruments ZSync link that provides both system-wide clock synchronization and data distribution. Furthermore, a 32-bit DIO VHDCI interface can be used to directly connect the SHFQC to other instruments of the QCCS, such as the HDAWG and the PQSC, for direct feedback or to third-party instruments.
No: the SHFQC can be controlled with a conventional computer. However, for optimal synchronization with other instruments of the QCCS, we strongly recommend using a PQSC.
No. The SHFQC can be used as a standalone system and provides everything needed to control and read out multi-qubit systems, including frequency conversion up to 8.5 GHz. It can be triggered through an internal trigger source or with any conventional TTL signal generator.
Yes. In a QCCS setup, the SHFQC is recommended for single-qubit control pulses and parametric two-qubit gates, whereas the HDAWG is ideal for flux-bias two-qubit gates.
Yes: up to 18 SHFQCs can be synchronized through a PQSC, leading to coordinated control of up to 108 qubits. The SHFQCs synchronized through a PQSC can be programmed with the LabOne QCCS Software, with LabOne, or with LabOne's APIs for Python; this affords flexibility in how best to incorporate the SHFQC into a new or an existing setup.

SHFQC-16W

Integration Weights Extension Option

Key Features

Doubles the number of integration weights from 8 to 16

Doubles the number of waveform memories from 8 to 16

Enables readout of up to 16 qubits, 8 qutrits or 5 ququads

Learn more

8.5 GHz Qubit Controller

Key Features

Variants

Price

Documents

Channel configurations for the SHFQC Qubit Controller

Quantum computing applications

Supported qubit types

Other applications

High-fidelity qubit manipulation and readout

Efficient workflow and resource handling

Fast readout with high fidelity

Scalable system approach

Quantum system control software

General

Signal generator signal outputs

Waveform generation

Quantum analyzer signal outputs

Readout pulse generator

Quantum analyzer signal inputs

Qubit measurement unit

Markers and triggers

General

Instrument Functionality

Signal Generator Functionality

Quantum Analyzer Functionality

Hardware

Software

System Integration

SHFQC Available Options

Integration Weights Extension Option

Key Features