Intra-CREATE: N-GAP: Nanophotonic GAtes with exciton-Polaritons

CNRS@CREATE is pleased to announce, as host institution, the selection of the project “N-GAP: Nanophotonic GAtes with exciton-Polaritons as an INTRA-CREATE project.

PIs and partners

Project team members

Prof Alberto Bramati

Lead PI Alberto BRAMATI

GAO Weibo

Lead co-PI GAO Weibo


N-GAP: Nanophotonic GAtes with exciton-Polaritons

One of the main goals in the field of quantum technologies is to achieve quantum computing. By exploiting genuine quantum features, such as quantum entanglement and quantum superposition, a quantum computer will realize tasks that are out of reach for any classical computer.

An ideal large-scale quantum computer should tackle the following challenges (the DiVincenzo criteria): a high qubit number (scalability), a low error rate (fidelity), the ability to perform all possible operations (universality), and an easy read-out. Many technologies and platforms have been suggested to build a quantum computer, including ions, atoms, electrons, and superconducting materials. Among these options, all-integrated photonic platforms that allow creating complex circuitry with a small footprint are very promising. The main advantage of using photons as information carriers is their ability to travel long distances with minimal decoherence, enabling the realization of several operations before information is lost.

However, this same advantage is also the main limitation of photons, as they do not interact.

Photonic platforms have so far been limited to use linear operations and their computing advantage is mainly due to the number of elements added and to the resulting complexity of simulations, rather than an inherently quantum operation that cannot be replicated classically.

Therefore, achieving specific controlled photonic quantum gates, such as CNOT, CZ, or Cubic Phase gate, in a deterministic and scalable way, is particularly interesting from the technological and applied point of view, but also extremely challenging due to the need for strong non-linearities.

In N-GAP we will explore and exploit a hybrid state of light and matter, the excitonic polariton, to create a platform for quantum computing. Exciton polaritons, which emerge from the strong-coupling of an exciton and a photon, exhibit Kerr nonlinearities typically three orders of magnitude stronger than that found in standard photonic nonlinear crystals. This advantage has led to the observation of effects such as superfluidity and ultra-efficient four-wave mixing, and polaritons have been used to implement ultra-fast optical switching, transistors and ultra-low threshold lasers.

The main objective of N-GAP is to further enhance the nonlinearity of the polariton systems to enter the full quantum regime. The achievement of the polariton quantum blockade is the necessary intermediate step towards the first experimental realisation of a deterministic CNOT gate based on polariton systems. To achieve this ambitious goal, we will study two different platforms providing giant optical nonlinearities: mature GaAs-based optical vertical microcavities and waveguides, as well as cavities and dielectric waveguides embedding novel 2D materials. The waveguide geometry is fully compatible with on-chip geometries opening the way to a large integrability and scalability in quantum optical circuits.

This research is supported by the National Research Foundation, Prime Minister’s Office, Singapore under its Campus for Research Excellence and Technological Enterprise (CREATE) programme.

CREATE is an international collaboratory housing research centres set up by top universities. At CREATE, researchers from diverse disciplines and backgrounds work closely together to perform cutting-edge research in strategic areas of interest, for translation into practical applications leading to positive economic and societal outcomes for Singapore. The interdisciplinary research centres at CREATE focus on four areas of interdisciplinary thematic areas of research, namely human systems, energy systems, environmental systems and urban systems. More information on the CREATE programme can be obtained from

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