Solid-State Cryogenic Heat Pump Using Adiabatic Electron Expansion
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Solution Overview
Problem
Current quantum computers are limited in size and complexity due to the cumbersome nature of dilution refrigerators required for cooling, which also deplete rare helium gas reserves, hindering advancements in quantum computation and materials research.
Innovation Solution
A cryogenic solid state heat pump device utilizing a central reservoir to isolate and expand electrons through a Carnot cycle, achieving cooling by adiabatic expansion and compression in a semiconductor quantum well, replacing traditional dilution refrigerators with a compact, on-chip solution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If dilution refrigerators are used for cooling quantum computers, then cooling capability is achieved, but device complexity and size increase significantly
Solution Approach 1:
The patent replaces the mechanical dilution refrigerator system with an electrical solid-state cooling device. The invention uses voltage-controlled electron gas expansion and compression in a semiconductor quantum well to achieve cooling, eliminating mechanical pumps, pumping lines, and large tanks. This substitution of mechanical systems with electrical control achieves the same cooling function with dramatically reduced complexity.
Solution Approach 2:
The invention changes the physical state and parameters of electron gas in a semiconductor quantum well by applying voltage. By controlling the voltage applied to the quantum well, the electron gas can be expanded into multiple subbands (adiabatic expansion for cooling) or compressed back to the ground state (adiabatic compression for heat rejection). This parameter control enables a compact solid-state cooling cycle.
2Temperature
If dilution refrigerators are used for cooling, then cooling power is provided, but helium gas consumption increases
Solution Approach 1:
The solid-state cooling device uses voltage-controlled electron gas as the refrigerant, eliminating the need for external helium gas supply. The electron gas in the semiconductor quantum well serves its own cooling function through voltage-controlled expansion and compression cycles, making the system self-sufficient and independent of helium gas reserves.
3Temperature
If dilution refrigerators are used, then cooling is achieved, but the system occupies large space
Solution Approach 1:
By replacing the mechanical dilution refrigerator with a solid-state electronic device, the system volume is dramatically reduced. The invention implements cooling functionality directly on-chip using voltage-controlled electron gas in a semiconductor quantum well, eliminating the need for room-filling equipment and enabling compact integration.
Solution Approach 2:
The solid-state cooling device integrates multiple functions into a single compact structure. The same voltage-controlled electron gas system performs both cooling (through expansion) and heat rejection (through compression), eliminating the need for separate systems and reducing overall volume.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This technology provides efficient cryogenic cooling, potentially cooling to 1 mK, reducing helium consumption and enabling scalable quantum computers with robust, all-electrical cooling, independent of helium supply, and offering a factor-of-3 cooling per cycle with cascaded stages.
Implementation Method 1
The electrons are isolated in the central reservoir and expanded from a single subband state into a multi-subband state when the device is selectively operated at a first stage
Implementation Method 2
Heat from the first reservoir is exchanged with the central reservoir when the device operates a second stage responsive to the device operating at the first stage
Implementation Method 3
The electrons are isolated and compressed in the central reservoir from the multi-subband state to the single subband state when the device is selectively operated at a third stage subsequent to the heat being exchanged between the first reservoir and the central reservoir
Implementation Method 4
Excess heat in the central reservoir generated during the second stage is ejected into the second reservoir when the device operates at a fourth stage responsive to the device operating at the third stage
Data Source
AI summary
Systems and/or methods can provide for solid-state refrigeration below 1 degree Kelvin. By applying a simple sequence of ac electrical signals to a gated semiconductor device, electrons are cooled in a refrigeration sequence that, in turn, provides cooling directly to the heat load of interest. Electrons in a single subband of a semiconductor quantum well are expanded adiabatically into several subbands, resulting in a temperature drop. Repeated application of this cycle at MHz-GHz frequencies results in a significant cooling power. The anticipated cooling powers can compete with today's standard cryogenic system, the dilution refrigerator, which represents the market standard for achieving cryogenic temperatures.