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QCCS Qubit Readout

High fidelity, speed and scalability are essential for optimal qubit readout. Operating at the critical interface between the quantum and classical regimes, Zurich Instruments' quantum analyzers ensure optimum algorithm performance on all available system sizes within reach today.

Superconducting qubit readout and state discrimination

High fidelity



Exceptional signal purity and high stability are key to maximizing readout fidelity, and so is the use of specialized signal processing such as matched filtering and digital demodulation. Zurich Instruments enables users to build on a technology that realizes the full potential of their quantum processor.

Use of signal lines can be optimized by reading out up to 16 qubits per channel in a frequency-multiplexed way. The functionality is available through a high-level software interface that does not require FPGA programming, so that the focus can stay on the quantum engineering challenges.

Zurich Instruments' quantum analyzers are designed for low latency, enabling a speed-optimized readout through weighted integration. Readout results are available on the ZSync interface for integration into the QCCS, as TTL signals for interfacing with other instruments and as level 0, 1, and 2 data visualized on a computer.

Application Use Cases

Use the SHFQA Quantum Analyzer for large-scale quantum computing with superconducting qubits:

  • Operation at up to 8.5 GHz without the need for mixer calibration
  • Measurement of up to 64 qubits without additional hardware such as LOs or mixers
  • Spurious-free detection bandwidth of 1 GHz, optimized for speed and fidelity
  • Multi-state discrimination and user-friendly result visualization

Use the UHFQA Quantum Analyzer for smaller quantum computing setups:

  • Matched filtering for optimal fidelity and multi-qubit readout capability
  • A detection bandwidth of 1.2 GHz provided by I and Q channels with 600 MHz bandwidth each
  • Free combination with any local oscillator, thus affording single-channel granularity

Use the UHFLI Lock-in Amplifier for RF reflectometry readout of semiconductor spin qubits:

  • Fully digital signal processing up to 600 MHz with clean signals and no mixer calibration
  • Multi-frequency capability without signal loss
  • Analysis of signals at all points in the chain thanks to the LabOne toolset
  • One software interface covering all major experimental methods: MFLI for transport, HDAWG for RF pulse generation, UHFLI for RF readout

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