Researchers have demonstrated the ability to trap and control individual electrons at temperatures more than 100 times warmer than what is required for most of today’s leading quantum computers, a breakthrough that addresses one of the most significant engineering challenges in the field. The achievement, operating above 1 Kelvin (approximately -458 degrees Fahrenheit), could dramatically simplify the complex and costly cooling systems needed for quantum machines, potentially accelerating the development of larger and more practical quantum processors.
This milestone, achieved by the quantum computing company EeroQ, validates long-standing theoretical predictions about using electrons on superfluid helium as a basis for exceptionally stable and pure quantum bits, or qubits. By proving that these qubits can function in a less extreme thermal environment, this work opens a new avenue for designing and building scalable quantum computers that are less constrained by the immense heat-dissipation problems that have limited progress. The method is notably compatible with existing superconducting hardware, offering a viable path for integration into current quantum systems.
A New Temperature Frontier for Quantum Bits
A significant barrier in quantum computing has been the extreme cold required to maintain the delicate quantum states of qubits. Most leading platforms, such as superconducting and spin-based qubits, must operate near absolute zero, typically around 10 millikelvin. This requires the use of large, specialized dilution refrigerators. In a paper published in the journal Physical Review X, researchers at EeroQ detailed the first-ever demonstration of trapping, detecting, and controlling single electrons at temperatures above 1 K.
This represents a temperature increase of more than two orders of magnitude, a crucial step toward more manageable operating conditions. While still incredibly cold by everyday standards, the difference between millikelvin and Kelvin temperatures is vast in terms of cryogenic engineering. Operating above 1 K moves quantum computing away from the most extreme and restrictive cooling technologies, making the prospect of building larger, more powerful machines much more feasible.
The ‘Electron-on-Helium’ Method
The innovative approach centers on trapping single electrons in the space just above the surface of superfluid helium. This environment is considered one of the cleanest in physics, providing a pristine system that isolates the electron—acting as the qubit—from environmental noise that can destroy its quantum state, a phenomenon known as decoherence. The electrons essentially float, held in place by underlying electrodes.
Superconducting Circuit Integration
To manipulate and read the state of these trapped electrons, the researchers employed on-chip superconducting microwave circuits. A specialized component called a coplanar waveguide resonator is used to sense the charge state of the electron trap. As electrons are loaded into the trap, their interaction with the resonator’s microwave field causes a measurable shift in its resonance frequency. This technique is sensitive enough to detect the presence or absence of a single electron, even in a comparatively noisy thermal environment above 1 K. Crucially, this method is compatible with the fabrication techniques and hardware already used in many superconducting quantum computers.
Overcoming a Major Scaling Hurdle
The primary benefit of this higher-temperature operation is the simplification of cooling infrastructure. The dilution refrigerators required to reach millikelvin temperatures are a major bottleneck for scaling up quantum processors. They are not only expensive and bulky but also have very limited cooling power, meaning they can only remove a tiny amount of heat generated by the quantum chip and its control wiring. This severely restricts the number of qubits that can be integrated into a single processor without causing overheating.
By moving to a “warmer” 1 K environment, researchers can utilize cryogenic systems with much greater cooling capacity. For example, a cryostat’s cooling power at 1 K can be orders of magnitude higher than at 10 millikelvin, allowing it to support far more qubits and the associated control electronics without becoming overwhelmed by heat. This capability is seen as a key enabler for building quantum machines with thousands or even millions of qubits, a necessity for solving commercially relevant problems.
Validating a Long-Held Theory
The experiment provides the first concrete validation of a long-standing theory that electrons on helium could serve as high-quality qubits without extreme refrigeration. For years, this system was predicted to offer an exceptionally “clean” environment, shielding the qubits from the defects and disturbances common in solid-state materials. This purity is expected to lead to very long coherence times, meaning the qubits can hold their quantum information for extended periods, allowing for more complex calculations.
The results published in Physical Review X confirm that these benefits hold even at temperatures where thermal energy is significantly higher than the electron’s motional frequency. The team’s observations of clear, reproducible frequency shifts from single electrons matched their theoretical models, establishing that precise control and readout are feasible in this new temperature regime.
Future of Quantum Computing Architectures
This breakthrough paves the way for new designs of quantum processors. EeroQ, founded in 2017, aims to combine the electron-on-helium approach with standard superconducting circuits to create a hybrid architecture. Such a system would leverage the advantages of both technologies: the stability and purity of electron qubits and the advanced control and readout capabilities of superconducting hardware.
The ability to operate at higher temperatures fundamentally changes the engineering trade-offs in designing a quantum computer. It reduces barriers to scaling and could lead to more modular and flexible designs. By easing the cryogenic burden, this work allows researchers to focus more on increasing qubit count and improving the quality of quantum operations, accelerating the timeline toward fault-tolerant quantum computers that can tackle problems beyond the reach of classical machines.
