Micorwave control system

1 The name of the procuring entity:

Chalmers Tekniska Högskola AB (Chalmer university of Technology), Avdelningen för Planering, Analys och Ekonomi/Procurement Department, on behalf of The Microtechnology and Nanoscience Department (The Wallenberg Centre for Quantum Technology (WACQT)).

Procurement officer, Lambros Andréasson (on behalf of Chalmers, lambros.andreasson@sidecore.se).

2 Description of the purpose of the contract and justification for Chalmers decision to award the contract without prior publication of a procurement notice in Mercell Tendsign and TED.

The Wallenberg Centre for Quantum Technology (WACQT) is on the quest to build a quantum computer based on superconducting technology. So far, the team has had put strong effort in building high-quality small scale quantum processors, starting from the development of a-few-qubits quantum processor. While the centre focusses on the building of the processor and its infrastructure, it procures the hardware to control the quantum processor by third party.

Since 2022, the team is working on demonstrating the operation of a 25-qubit processor (only 20 qubits are accessible because of the limited number of cables in the present set-up). In 2021, a public procure-ment was set to buy the needed control hardware and Qblox was awarded the contract.

Figure 1 (a): The quantum processor is cooled down inside a cryostat. Experiments are performed by sending precise sequences of electrical signals and measuring the electrical signal sent back from the processor, via the control hardware. The hardware is controlled via a dedicated control software. (b) and (c): The Qblox hardware. Control or readout module (b) are inserted in a pre-mounted 19” rack system, named the Cluster (c). Qblox system ensures that modules within the same or different cluster are fully synchronised. (Images taken from www.qblox.com)

The quantum processor sits at cold temperature inside a cryostat, and it’s controlled and readout by the control hardware by sending and reading electrical signals (Fig. 1(a)). The control hardware is controlled by a PC through a dedicated software package. Qblox’s full system comprises multiple quantum pro-cessor control and readout modules (see Fig. 1 (b) and (c)) that are pre-mounted in a 19” rack system together with appropriate power supplies and all necessary accessories. The system is fully optimised to achieve synchronization amongst all modules. Qblox’s offer also includes a software package called Quantify, designed for defining and performing complex experiments. The WACQT’s team has built the quantum computer’s software infrastructure around the Quantify package and the Qblox instrumentation.

As next milestone, WACQT aims to demonstrate the operation of a 57-qubit quantum processor by 2024. In parallel to this effort in scaling up, a 25-qubit quantum processor (referred to as the testbed) will be made available to Swedish industry, an activity that will be outsourced to the company Chalmers NextLab. Hardware for these two systems and smaller upgrades to existing systems will need to be pro-cured.

Technical reasons

WACQT needs to procure the same control hardware to set up the additional quantum processors (the testbed, WACQT’s own 57-qubit. To achieve these ambitious milestones, we require 100% compatibil-ity between all setups for both hardware and software. Otherwise, it would not be possible to use the already developed infrastructure. Developing a new software infrastructure with hardware procured by a different vendor will drastically delay our progress by 2-3 years.

WACQT needs to buy the hardware from Qblox, for the following technical reasons:

• The procured system must be compatible with the already procured hardware. Qblox provides a so-lution (the Cluster) that allows the user to slot in additional units to scale up the number of qubits to be controlled in the quantum processor (see Fig. 1 (b) and (c)).

• The single units are fully synchronised amongst them. This is a crucial characteristic as we need to be able to send electrical pulses that are synchronised at nanosecond level. Qblox guarantees syn-chronisation both between units that are inserted in the same cluster and between units that are in different clusters. For this reason, WACQT cannot mix the already acquired Qblox hardware with solutions offered by other vendors as there is no guarantee that we would be able to control the quantum processor with the same level of accuracy.

• WACQT is also working on building up the software infrastructure that will allow its own quantum processor to be available on the cloud. The software infrastructure needs to be built around the pro-cured hardware and WACQT is currently developing this infrastructure around Quantify, the soft-ware that controls the Qblox hardware.