A Cryogen-free Helium Dilution Refrigerator for Quantum Information Science
Abstract
Quantum bits (qubits) formed from superconducting resonant electrical circuits are one of the most promising quantum information technologies today. They combine compact size with long-lived coherence, strong addressability, and easy coupling, allowing for the possibility of scaling to large quantum processors. In order to achieve optimal performance, these qubits must be operated at very low temperature. The relevant temperature scale is set by the qubits’ resonant frequencies, which are in the microwave regime (roughly 5 GHz). This frequency range means that a circuit can be considered “cold� if its temperature is significantly below 0.25 K (0.25 degrees Celsius above absolute zero). It is thus necessary to cool the qubits down below roughly 20 mK (20 thousands of a degree Celsius above absolute zero). There is only one technology which currently exists to cool macroscopic objects to this temperature and keep them there indefinitely- a helium dilution refrigerator. Such a refrigerator uses vacuum pumps and compressors to precisely mix two isotopes of helium in such a way that evaporation of one isotope cools the system. This proposal details a closed-cycle “cryogen-free� dilution refrigerator that can cool a volume of 16 L to a temperature of 10 mK and hold that temperature indefinitely without consuming liquid helium. The refrigerator is outfitted with heavily attenuated and filtered microwave and dc wiring for the control and measurement of superconducting qubit devices. It contains light-tight infrared radiation shielding to maintain qubit coherence and has a large sample volume and cooling power sufficient to cool many qubit devices and their supporting hardware. The system is the basis for multiple independent measurement apparatuses useful for quantum information science experiments. It is a single purchase with a total price of roughly $680,000.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Mar 06, 2024
- Source ID
- FA95502310431
Entities
People
- Eli Levenson-Falk
Organizations
- Air Force Office of Scientific Research
- United States Air Force
- University of Southern California