The RF iteration of the Qubit Readout Module (QRM-RF) provides all necessary capabilities for qubit readout without the need to manually up and down convert signals. This allows for the device to synthesize and acquire signals in the range of 2-18.5GHz using internal RF conversion stages.

QRM-RF front panel

On the front of a QRM-RF module you will find the following components:

  • 2 x SMA female (receptacle) connectors: 1 output (O[1]: @ 50 Ω) ; and 1 input channel (I[1]: @ 50 Ω).

  • 2 x SMP male (pin) connectors: Marker output channels (0-3.3 V TTL).

  • 6 x status LEDs: See section Frontpanel LEDs.

The operation of the module is similar to the standard QRM, with 6 Q1 sequence processors onboard. Each sequencer is connected to the output markers, as well as the input and output paths. Using parametrization, each sequencer can target one qubit for readout, allowing multiplexed readout of multiple qubits on the same channel. The AWG paths can generate the readout pulses and the acquisition paths can process the returned readout data. The acquisition path supports any combination of three acquisition modes:

  • Scope: Returns the raw input data.

  • Integration: Returns the result after integrating the input data;

    optionally based on an integration function stored in memory.

  • Thresholded: Returns the binary qubit value after thresholding

    the integrated value.

The results of the acquisitions are returned to the user through the qblox_instruments driver.

For a list of available features please go to Features

For an overview of applications please go to Applications

Block Diagram#

Block diagram of a Qubit Readout Module

The QRM-RF module contains the following features:

1. 10MHz Reference

2. Trigger



5. Q1 Sequencer

6. Marker output channels

7. Sequencer Multiplexer

8. Digital Offset

9. DAC and ADC

10. Offset DAC

11. Local Oscillator

12. IQ Mixer

13. Variable Attenuator

14. Output Switch


1. 10MHz Reference#

Alongside all modules available, the QRM-RF module operates with respect to a 10MHz reference provided by the cluster.

2. Trigger#

The trigger of the QRM-RF is connected to the cluster and allows for fast synchronization between modules.

3. SYNQ#

The Qblox SYNQ technology enables simple and quick synchronization over multiple instruments, allowing for modules to be started synchronously << 1ns. See section Synchronization for more information.

4. LINQ#

The Qblox LINQ technology allows for the results of measurements to be shared between devices, distributing outcomes in < 320ns.

5. Q1 Sequencer#

The Q1 sequencers are the heart(s) of the QRM-RF instrument. They orchestrate the experiment using a custom low-latency sequence processor specifically designed for quantum experiments. Each Q1 sequencer controls a dedicated AWG path and, in the case of a QRM/QRM-RF, an acquisition path, which enables parametrized pulse generation and readout. Each instrument has 6 of these sequencers to target multiple qubits with one instrument. See section Q1 Sequence Processor for more information on how to program and control them.

Each sequencer has a dedicated gain step for both path 0 and 1, which can be statically configured using the Sequencer.gain_awg_path0() parameters. However, the gain can also be dynamically controlled using the set_awg_gain instruction of the sequence processor which enables pulse parametrization (see section Instructions). The static and dynamic gain controls are complementary.


Since the QRM-RF module has integrated IQ mixing, the gain Sequencer.gain_awg_path0() has to be the same for both paths.

Each sequencer has a dedicated numerically controlled oscillator. The NCO can be used to track the qubit or resonator phase (at a fixed frequency) and the IQ mixer can be used to modulate the output.

The frequency of the NCO and phase can be statically controlled using the Sequencer.nco_freq() and Sequencer.nco_phase_offs() parameters. However, the phase of the NCO can also be dynamically controlled using the set_freq, reset_ph, set_ph and set_ph_delta instructions of the sequence processor, which enables pulse parametrization and execution of virtual Z-gates (see section Instructions). The static and dynamic phase control is complementary. The modulation is enabled using the Sequencer.mod_en_awg() parameter. The demodulation is enabled using the Sequencer.demod_en_acq() parameter.

Each sequencer can perform averaging and binning of measurement of results. Integration and state assignment of data can also be performed on board, outcomes of these measurements can then be shared via LINQ within 320ns.

6. Marker output channels#

Each sequencer has control over the four marker output channels, with the control of each sequencer being OR’ed to create the final marker outputs. The markers can be dynamically controlled with the set_mrk instruction of the sequence processor (see section Instructions), but can also be overwritten with the static marker overwrite parameters Sequencer.marker_ovr_en() and Sequencer.marker_ovr_value(). The marker output range is 0-3.3 V TTL. In the QRM-RF module set_mrk is also used to toggle the switches before the outputs/inputs to enable the respective output/input. For the QRM-RF module, bit indices 0 & 1 correspond to input 1 and output 1 switches respectively, indices 2 & 3 correspond to marker outputs 1 and 2 respectively.

6.1 Setting Markers as Active HIGH/LOW#

The default state of marker is active high (OFF = 0V, ON = 3.3V). Users have the ability to change the marker output from active HIGH to active LOW ( OFF = 3.3 V, ON = 0V). It can be done using the parameter QRM_RF.marker0_inv_en(). This inversion of marker default states is possible for all marker channels. Here marker0 and marker1 correspond to bit indices 2 & 3 respectively in in the argument of set_mrk as mentioned above.

7. Sequencer Multiplexer#

A multiplexer that allows any sequencer to be connected to any output. Multiple sequencers can also be connected to a single output. This, in combination with the dedicated NCO per sequencer and the IQ mixer, enables easy and flexible targeting of multiple resonators on a single channel. See Multiplexing for more details.


The output of each sequencer is complimentary. Be aware of potential output clipping when connecting multiple sequencers to a single output.

8. Digital Offset#

Each sequencer has a dedicated offset step for both path 0 and 1, which can be statically configured using the Sequencer.offset_awg_path0() parameters. However, the offset can also be dynamically controlled using the set_awg_offs instruction of the sequence processor which enables pulse parametrization. (see section Instructions). The static and dynamic offset controls are complementary.


This offset is applied to the signals before the mixer and cannot be used for DC offset correction if the mixer is enabled.

9. DAC and ADC#

The dynamic output range of the QRM-RF’s DACs is 5 Vpp and 50 Ω terminated at 1GBps.The maximum input range of the QRM’s ADCs is 2 Vpp and 50 Ω terminated.


The 12-bit ADCs have a fixed range of 2 Vpp. When performing acquisitions the input should be an order of magnitude such that the resolution (0.5mV) of the ADC can accurately define the measured signal. Gain or attenuation stages may be required at the input to compensate for this. See 13. Variable Attenuator for the attenuation onboard the device.

10. Offset DAC#

The offset DAC allows users to apply a DC offset to the output signal without the risk of clipping the signal at the DAC.

11. Local Oscillator#

The QRM-RF module comes equipped with its own built-in local oscillator capable of generating signals between 2.5 and 18GHz for IQ mixing.

12. IQ Mixer#

The QRM-RF module also has onboard IQ mixers for both the output and acquisition. The LO’s of these internal mixing stages are capable of sweeping between 2-18.5GHz. This allows for the generation and acquisition of signals at the qubit and readout resonator frequency respectively.

13. Variable Attenuator#

The QRM-RF module has a variable attenuator, which can be programmed, on both the input and output terminals. The output attenuation can be programmed to be between 0 to 60 dB in 2 dB steps whilst the input attenuation can be set between 0 to 30 dB in 2 dB steps.

14. Output Switch#

The output terminal of the QRM-RF can be toggled with an inbuilt switch.


The Qubit readout module is designed to be utilized for the measurement of qubits. The experimental setup will vary depending on the device being controlled:

Superconducting Qubits#

The QRM-RF can be utilized to create a readout pulse with its outputs and corresponding acquisition for a multi qubit device. Frequency division multiplexing can be utilized to readout multiple qubit states simultaneously (up to 6). The outputs of a QRM-RF can also be utilized as arbitrary outputs (e.g. for a charge line) if needed. As the QRM-RF module has an on-board IQ mixer for both generation and acquisition it can interface directly with the drive and readout lines of the circuit. The details of such a setup are provided here: Superconducting Qubits.

Spin Qubits#

The QRM-RF provides readout capability for measuring spin qubits in GaAs, Si or Ge quantum dots. The QRM-RF is capable of performing qubit measurements via charge sensing, RF reflectometry, gate-based readout or via microwave resonators. As the QRM-RF module has an on-board IQ mixer for both generation and acquisition it can interface directly no external RF-mixing circuitry is required. of the circuit. Details of potential setups and applications are available here: Spin Qubits.

NV-centers/Spins in Diamonds#

The QRM-RF can be used to perform measurements on spins in diamond by connecting it to a qubits microwave resonator. The QRM-RF module will be able to synthesize frequencies in the range required for readout. Details of potential setups and applications are available here: NV-centers.

Absolute Maximum Ratings#


This section shows the absolute maximum ratings of the cluster QRM-RF module. Operation beyond these values can damage the module and cluster!







Input Power

15 dBm








Number of channels


Output coupling


DAC resolution


Output impedance


Output power

In 50Ω load









Number of channels


Input coupling


ADC Resolution


Input impedance


Input power


Marker Outputs#






Number of markers


High voltage

high Z load


Low voltage