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Strategic Research Initiatives

Development Of A Scanning SQUID Microscope For Imaging Vortices In Superconductor Devices For Quantum Information Processing

Dale Van Harlingen ,Department of Physics; and Vidya Madhavan, Materials Research Laboratory

Addressing the Problem

Quantum information science is exploding and emerging as a primary research and technology driver worldwide. It has captured the attention of researchers exploring the new physics inherent in conventional superconducting qubits such macroscopic quantum phenomena, entanglement, and dephasing, and especially in the topologically-protected routes to quantum processing that have focused researchers on topological materials and devices. There is an international race to study such systems since they could be used to carry out quantum logic operations without dephasing, enabling a powerful form of quantum computing that is topologically-protected, leading to dramatic enhancements in computing speeds. A key issue in this field is need for new experimental tools and techniques optimized to probe and manipulate these exotic states and particles that have so far proven to be elusive and mysterious. Our plan is to develop new scanning probe instruments and measurement schemes designed to explore these excitations and to enable advanced technologies based on them.

Research Goals

Our goal is to develop a Scanning SQUID (Superconducting QUantum Interference Device) Microscope (SSM) that would operate at ultralow temperatures (down to 10mK) and with spatial resolution previously not achieved (down to and below 500 nm). This will be used to probe and manipulate vortices in hybrid superconductor-topological insulator superconductor devices that are predicted to host topological particles such as Majorana fermions, the key element in topologically-protected quantum computers. We will leverage our expertise and experience in scanning probe microscopy and superconducting device physics, and rely on support from our strong programs in condensed matter physics and materials science.

Current Activities

We are currently working simultaneously on many fronts to design and construct the SSM instrument and demonstrate its capabilities:

  • Design and construction of the scanning probe microscope
  • Design and fabrication of the SQUID sensor for magnetic field detection
  • Optimization of the electronics for magnetic imaging with the SQUID sensor
  • Testing of the scanner in a He-3 system down to 300mK
  • Planning for porting the system into a dry (helium-free) dilution refrigerator for imaging and simultaneous transport measurements down to 10mK
  • Simulations of vortex and Majorana fermions dynamics in hybrid superconductor-topological insulator systems to correlate with imaging experiments