QCM-RF#

Description#

The RF Qubit Control Module (QCM-RF) is an instrument completely dedicated to qubit control using parametrized pulses. The front of a QCM-RF module is presented below:

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

2 x SMA female (receptacle) connectors: 2 outputs (O^[1-2] @ 50 Ω).
2 x SMP male (pin) connectors: Marker output channels (0-3.3 V TTL).
6 x status LEDs: See section Frontpanel LEDs for details.

The pulses generated by the QCM-RF are stored as waveform envelopes in memory and can be parametrized by changing gain and offset and additionally phase, if also modulated. This parametrization is controlled by the AWG paths of the Q1 sequencer (Description), which each have two waveform paths (from here on referred to as path 0 and 1). Using parametrization, the output of these paths can be operated as modulated IQ signals, which are connected directly to the onboard IQ mixers. The two paths of each sequencer can, in turn, be connected to any output of the instrument (i.e. O¹ and O²). Additionally, the sequencers also control two marker output channels. The RF version of the QCM has two IQ mixers on-board for generating signals at its outputs in the range of 2-18.5GHz.

For a list of available features please go to Features

For an overview of applications please go to Applications

Block Diagram#

1. 10MHz Reference	2. Trigger
3. SYNQ	4. LINQ
5. Q1 Sequencers	6. Marker output channels
7. Sequencer multiplexer	8. Digital Offset
9. DAC	10. Offset DAC
11. Local Oscillator	12. IQ Mixer
13. Variable Attenuator	14. Output Switch

Features#

1. 10MHz Reference#

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

2. Trigger#

The trigger of the QCM-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 Sequencers#

The Q1 sequencers are the heart(s) of the QCM-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 QCM/QCM-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.

Note

If modulated IQ signals are used for an output pair, 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 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 has the ability to 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 200ns.

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 QCM-RF module set_mrk is also used to toggle the switches before the outputs to enable the respective output. For the QCM-RF module, bit indices 0 & 1 correspond to output enable 1 and 2 respectively, indices 2 & 3 correspond to marker outputs 2 and 1 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 QCM_RF.marker0_inv_en(). This inversion of marker default states is possible for all marker channels. Here marker0 and marker1 correspond to bit indices 3 & 2 respectively 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 IQ mixer per output, enables easy and flexible targeting of multiple qubits on a single channel. See Multiplexing for more details.

Note

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.

Note

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#

The dynamic output range of the QCM-RF’s DACs is 1 Vpp and 50 Ω terminated at 1GBps.

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 QCM-RF module comes equipped with built-in independent local oscillators for each output capable of generating signals between 2.5 and 18GHz for IQ mixing.

12. IQ Mixer#

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

13. Variable Attenuator#

The QCM-RF module has variable attenuators on both the output terminals. These attenuators can be programmed from 0 to 60dB in 2dB increments.

14. Output Switch#

The output terminal of the QCM-RF can be toggled with an inbuilt switch, which can also be controlled dynamically with the Q1 processor.

Applications#

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

Superconducting Qubits#

The QCM-RF can be utilized to generate superconducting qubit drive frequencies. As the QCM-RF module has onboard IQ mixers for the generation of pulses it can interface directly with the drive lines of the qubits. The details of such a setup are provided here: Superconducting Qubits.

Spin Qubits#

The QCM-RF module can be used to generate control signals for GaAs, Si and Ge spin qubits. As the QCM-RF module has on-board IQ mixers for the generation of pulses it can synthesize control pulses directly at the qubit frequency with no need for external RF mixing circuitry. Details of potential setups and applications are available here: Spin Qubits.

NV-centers/Spins in Diamonds#

The QCM-RF module can be used to generate control pulses for spins in diamond. As the QCM-RF module has on-board IQ mixers for the generation of pulses it can synthesize control pulses directly at the qubit frequency with no need for external RF mixing circuitry. Details of potential setups and applications are available here: NV-centers.

Specifications#

Output#

Parameter	Condition	Min	Typ	Max
Number of channels			2
Output coupling			AC
DAC resolution			16bits
Output impedance			50Ω
Output power	In 50Ω load	-55dBm		5dBm

Marker Outputs#

Parameter	Condition	Typ
Number of markers		4
High voltage	high Z load	3.3V
Low voltage		0.0V