Color Centers#

One of the best-known types of optically addressable qubits is the color center. These are tiny defects in crystals that can absorb and emit light, which makes them especially useful for quantum communication and network applications. Their name comes from their light-emitting behavior: each defect emits photons at a specific frequency, or ‘color.’ By creating localized electronic states within the crystal, color centers can store and manipulate quantum information. Examples include nitrogen-vacancy (NV) centers in diamond, tin-vacancy (SnV) and germanium-vacancy (GeV) centers, as well as defects in silicon carbide. These systems are optically addressable, meaning their states can be manipulated and read using light, typically with precision lasers.

Architecture#

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Typical Qblox control electronics setup for a sample containing 3 color center qubits.#

Typical experiment with color-center qubits requires a variety of control pulses to manage their states, along with optical modulators to read them out by detecting photons. Qblox provides a range of products that make it easier to work with many different kinds of color centers.

  • QCM-RF enables RF qubit control for up to six qubits at a time.

  • QCM enables control of optical modulator (acousto-optical modulator or electro-optic modulator) for the different lasers in the setup (readout and spin pump lasers).

  • QTM enables counting and time-tagging fluorescent photons detected by photon detectors (APDs and SNSPDs).

The Qblox cluster allows users to flexibly extend their setup with these modules while ensuring intrinsic phase coherence and channel synchronization. In addition, the integrated low-latency feedback infrastructure enables conditional branching within experimental protocols.

On this page, we provide a number of solutions for tune-up and characterization for NV centers. They serve as demonstrations of our compiler Qblox scheduler.

To use a NV-center as a qubit platform, it should be characterized. It involves sequential experiments, where each step builds on the results of the previous one. The workflow for tuning a color center is illustrated in the accompanying figure.

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In this diagram, arrows indicate dependencies, showing that experiments are typically conducted from left to right.

One key experiment in characterizing color centers is Optically Detected Magnetic Resonance (ODMR), which is analogous to qubit spectroscopy. In this page we provide the building blocks to equip users to perform these experiments.