Variable temperature measurement system for quantum devices from strongly correlated and topological materials

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We propose to purchase a Variable Temperature Insert (VTI) for the study of quantum electronic devices, over an enormous temperature range covering the deeply cryogenic limits of 1.5K, all the way up to room temperature. Electronic devices offer a powerful platform to from which to study novel quantum mechanical effects, then in many cases to harness them for technological applications. One example of such "quantum devices" are qubits, the building block of quantum computers, which are based on long-lived quantum states that can only be found at the lowest available temperatures--within a few hundredths of a degree above absolute zero. Since arriving at UBC 15 years ago my group has specialized in the type of quantum devices that require ultra-low temperatures to access, and have built up a lab with several dilution refrigerators optimized for achieving such conditions. In the last few years, however, a new type of quantum device has emerged in which new materials, often based on 2D materials such as graphene, show quantum effects at much higher temperatures. These effects are typically based on strong interactions between the constituent electrons, or on topological protection. A beautiful example is twisted bilayer graphene, in which two sheets of graphene are deposited one atop the other with a precise angle misalignment between them. The resulting Moire pattern yields a material that can be tuned from superconductor to ferromagnet to correlated insulator with just a few volts on a nearby gate. This opens up the possibilities that were long hoped-for with strongly correlated materials, an field of particular expertise in Canada, but now in a material system that is as controllable as the transistor in a computer chip. Interestingly, the ultra-low temperatures appropriate for qubits and other "conventional" quantum devices are not only inconvenient, but may even hide the most interesting phenomena from study, making a VTI critical for the study of this new generation of devices. We will modify one of our existing measurement systems to fit the proposed VTI, taking advantage of the magnet cryostat already in our lab (thanks to previous CFI funding). The system will offer the fast access to a broad temperature range ideally suited to 2D materials, including twisted bilayer graphene. Our group has already established itself as a leader in quantum electronic device measurements in Canada; this funding will enable us to rapidly expand into the promising new area of strongly correlated and topological devices.