Quantum computing is on the cusp of a revolution, promising breakthroughs in numerous domains such as climate prediction, material design, and drug discovery. A series of pivotal milestones achieved by researchers from around the world provides a glimpse into this rapidly evolving domain.
The Pillar of Coherence Time Extended
Coherence is fundamental to effective communication, transcending disciplines from speech and writing to information processing. Qubits, the basic building blocks of quantum computing, exemplify this principle.
Extended Coherence Time: A team spearheaded by the U.S. Department of Energy’s Argonne National Laboratory, in collaboration with the University of Notre Dame, reported a remarkable enhancement in the coherence time of a new qubit type to 0.1 milliseconds. This is a colossal improvement—almost a thousand-fold—from the previous record.
Charge Qubits: Unlike conventional bits, these qubits can exist simultaneously in the 0 and 1 states. The team’s qubits encode quantum information in the electron’s motional (charge) states, earning them the title of ‘charge qubits’.
Unique Fabrication: The qubit consists of an electron trapped on a solid-neon surface within a vacuum. The use of neon is paramount, given its non-reactive nature, ensuring minimal disturbance to the electron, hence offering prolonged coherence time.
Highlights of the Achievement:
The new qubit type promises about 10,000 operations within its coherence time, a significant leap from the 10-100 operations feasible with conventional electron charge qubits. (source)
Innovations in the neon platform and reduction of disruptive signals resulted in the enhancement of the coherence time from an initial 0.1 microseconds to the current 0.1 milliseconds.
Another significant accomplishment was the successful coupling of two-electron qubits to a superconducting circuit, which paves the way for advanced two-qubit entanglement, a pivotal facet of quantum computing.
Atomic Precision in Spin-Based Qubit Platforms
Meanwhile, researchers in South Korea have introduced a quantum computing platform capable of operating multiple spin-based qubits simultaneously, pushing the boundaries of spin-based qubit advancements.
Precision Assembly with STM: Utilizing a scanning tunnelling microscope (STM), a tool renowned for its prowess in imaging and manipulating atomic scales, the Seoul-based team showcased the first-ever qubit platform assembled with atomic precision.
System Configuration: The entire system was meticulously assembled on a magnesium oxide bilayer film surface. This included a sensor qubit right below the STM tip and a pair of remote qubits on either side, precisely positioned outside the electron tunneling zone.
Magnetic Field Manipulation: Iron atoms were strategically placed to act as single-atom magnets, ensuring spin alignment for each remote qubit. Transitions between spin states were facilitated using electron spin resonance, applying radio-frequency pulses through the STM tip.
The Path Forward
While these achievements are significant, the teams acknowledge the need for further optimization. Efforts to extend coherence time and entangle multiple qubits are underway. With support from institutions like the DOE Office of Basic Energy Sciences and the Julian Schwinger Foundation for Physics Research, we can anticipate further groundbreaking advancements in the near future.
In conclusion, as quantum computing evolves, researchers across the globe are relentlessly pushing the boundaries, bringing us a step closer to unlocking its vast potential.