Semiconductor Quantum Photonics

Semiconductor based quantum photonic devices and circuits are highly promising for controlling light-matter interactions at the limit of single photons and individual electrons. Such systems provide wide scope for implementing various quantum (Q) information technologies, including Q-communication, Q-computation and exploring the fundamental properties of Q-matter.  For example, they can be used for (i) the deterministic generation of quantum states of light and the efficient storage & retrieval of quantum information in memories built from trapped electron and nuclear spins, (ii) the construction of stable quantum photonic circuits for quantum information processing and simulation and (iii) engineering of the effective photon-photon interactions in optical cavities and (iv) their use for preparing and studying quantum many body physics in strongly interacting quantum fluids of light.

The lecture will begin by introducing fundamentals including the optical control methods available from the "quantum optical toolbox" key theoretical aspects pertaining to light-matter couplings at the quantum limit.  We will then move on to explore technological and materials aspects, including the techniques used to produce semiconductor-based Q light sources and Q photonic circuits, as well as quantum detectors of light that can be integrated into nanophotonic circuits. In the second half of the module, our attention will shift to the application of these key concepts in the fields of Q-communication, -metrology and -sensing.  Finally, our attention will turn to strongly interacting quantum fluids of light in nanostructured semiconductor microcavities.  Specific topics will include:

• Fundamentals
• Historical motivation, scientific & technological context
• The quantum optical toolbox for near isolated quantum systems
• Jaynes-Cummings model for cavity-QED
• Quantum nonlinearities
• Open quantum optical systems - quantum master equations
• Strong and weak coupling regimes of cavity QED
• Technological Aspects
• Quantum emitters: self-assembled quantum dots + defects in crystalline solids.
• Photonic modes in resonators, waveguides and directional couplers.
• Material systems for integrated quantum photonics (silicon-based, III-V, diamond, lithium niobate and silicon-carbide)
• Quantum Photonic Technologies
• Quantum cryptography using discrete and continuous variables
• Photon based quantum simulation (Boson sampling)
• Linear Optics Quantum Computation (LOQC)
• Photonic cluster states and measurement-based approaches for QIP
• Quantum limited detectors based on semi-(super)conductors
• Quantum Fluids of Light
• Semiconductor microcavity designs (planar, tunable, plasmonic and hybrid)
• Microcavity polaritons
• Bose-Einstein condensation of MC-Polaritons (coherent and incoherent pumping)
• Superfluid hydrodynamics of the photon fluid
• Strongly correlated photons

After participation in the Module the student is able to:

1. Understand the rationale for building semiconductor-based quantum photonic devices and circuits.
2. Understand how semiconductor nanostructures can be used to generate, manipulate and detect quantum light.
3. Explain key-aspects of coherent light-matter interactions at the quantum limit, in the isolated and dissipative regime.
4. Describe key quantum photonic technologies including quantum cryptography, photonic quantum simulation and linear-optics-quantum-communication.
5. Explain how microcavity polaritons can undergo Bose-Einstein condensation and describe their non-linear quantum properties.
6. Make the device concepts related to interacting fluids-of-light comprehensible.

No prerequisites beyond the requirements for the Master’s program in Quantum Science and Technology.

The module consists of a lecture series (4 SWS), comprising two lecture sessions per week.

Quantitative concepts and analysis will be presented at the blackboard or via iPad+beamer. The latter will be used to discuss the implementation of experimental set-ups. These presentations will be complemented by videos, QuTiP simulations and practical experiments.

Combined Power Point and blackboard/iPad presentation, videos, simulations and experiments.

• Mark Fox - Quantum Optics: An introduction (Oxford University Press 2006)
• M.A. Nielsen and I.L. Chuang - Quantum Computation and Quantum Information (Cambridge University Press)
• Peter Michler - Quantum Dots for Quantum Information Technologies - (Springer, 2017).

There will be a written exam of 60 minutes duration. Therein the achievement of the competencies given in section learning outcome is tested exemplarily at least to the given cognition level using comprehension questions and sample problems.

For example an assignment in the exam might be:

• Describe the process of coherent light-matter interaction in the rotating-wave approximation.
• Summarize what will happen to the Rabi dynamics as a function of drive laser, two-level system detuning?
• Explain the fundamental principles of quantum cryptography using single photons and continuous optical fields?
• Describe how interactions can be generated between single photons in a semiconductor?
• How to detect if Bose-Einstein condensation has occurred in a microcavity?