The Quest for Photon Emitters

At the heart of quantum computing lies the manipulation of light, where individual particles of light, or photons, carry quantum information. A crucial element for the success of quantum technologies is the effectiveness of single photon emitters that can deliver precisely one photon at a time. However, achieving high quantum and collection efficiency—that is, the ability to emit photons on demand and ensure they are easily collected—has long been a challenge. Leading the charge is a team helmed by Professor Gao Weibo from NTU’s School of Electrical and Electronic Engineering and School of Physical and Mathematical Sciences. They have developed photon emitters using ultrathin 2D materials like tungsten diselenide (WSe2), achieving an average quantum efficiency of 76.4%, with some devices exceeding 90%. This remarkable feat represents one of the first instances of near-unity quantum efficiency being realized in 2D materials, approaching the theoretical maximum of 100%.

Supercharging the Emission Process

The innovative process involves utilizing a laser to generate excitons—temporary pairs of electrons and holes—in the WSe2 layer. As these excitons decay to their ground state, the challenge is to ensure that the decay is radiative, meaning that it results in the emission of a photon. By applying an electric field to manipulate the charges associated with the excitons, the research team significantly reduced the probability of non-radiative decay, ultimately maximizing photon emission efficiency. Professor Gao emphasized the potential applications of this technology in quantum communications and scalable optical quantum computation, making it a significant advancement in the field.

Transformative Designs in Photon Control

In addition to enhancing photon emitters, researchers have explored innovative means to control the speed of light—critical for the processing of quantum information. Traditionally, slowing light down in photonic chips leads to backscattering and transmission inefficiencies. However, a new design led by Professor Zhang Baile at NTU has effectively addressed these issues. Utilizing a photonic Chern insulator, researchers have managed to slow light over a broad frequency range without the drawbacks associated with backscattering. This breakthrough opens new avenues for applications such as quantum memory, which is essential for efficient quantum information processing.

Revolutionizing Quantum Circuits with Room Temperature Operations

An even more astonishing development comes from observations made by researchers led by Professors Wang Qi Jie and Wei Lei, who discovered ultra-strong coupling between excitons in tungsten disulfide (WS2) and surface plasmons at room temperature. This observation, a first of its kind, could eliminate the necessity for the ultra-low temperatures currently required in superconducting quantum circuits, significantly reducing the operational costs of quantum computers.

Drug Discovery Accelerated by Quantum Technologies

Not only do these advances offer potential for computational breakthroughs, but they also extend into the realm of healthcare. NTU scientists have engineered a quantum processing chip capable of utilizing photons to glean insights into the chemical properties of molecules, promising faster drug discovery processes. Employing a method called scattershot boson sampling, the researchers were able to simulate the vibronic spectra of various molecules. The implications are vast, enabling the rapid development of new pharmaceuticals by simulating complex molecules and their transitions.

With the ability to operate at room temperature and in a compact design, this chip stands poised to not only enhance quantum computing capabilities but also revolutionize how we approach scientific problem-solving in chemistry and medicine.

Conclusion

In summary, NTU's groundbreaking research in 2D materials and photon emission is paving the way for revolutionary advancements in quantum technologies, promising more efficient computing, innovative drug discovery, and practical applications that touch various facets of modern life. As these technologies evolve, the landscape of quantum science is set to change dramatically in the coming years.