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teaching

Quantum Information Technologies BSc elective

Since 2025–26 I coordinate the elective course “Quantum Information Technologies” (20741 – Tecnologías de la Información Cuántica) in the Bachelor’s Degree in Physics at UAM. The course follows Quantum Physics by Prof. Alexander Lvovsky (chapters 1, 2, 3 and 5):

  1. Postulates of quantum mechanics
  2. Entanglement and its applications
  3. Open quantum systems and decoherence
  4. Quantum harmonic oscillator and the Heisenberg picture

Advanced Quantum Communications lecture

Extension lecture at the DPG Physics School on Applied Photonics, Bad Honnef (Germany), September 2026: from the quantum description of light and photon detection (POVMs) to QKD — BB84, weak coherent vs. true single-photon sources, decoy states and recent experimental milestones.

Slides · Mathematica notebook with plots and simulations

Photons in Quantum Computing lecture

Invited lecture “Fotones en computación cuántica: tecnología y perspectivas” at the UPV/EHU Summer Course “Quantum Computing: from Fundamentals to Applications”, San Sebastián (Spain), September 2025: photonic qubit encodings and linear-optics gates, heralded vs. deterministic single-photon sources and squeezed light (GKP states), single-photon and photon-number-resolving detectors, boson sampling vs. measurement-based computing on cluster states, and the platforms of PsiQuantum, Quandela and Xanadu.

Slides

Solid-State Quantum Technologies MSc

Since 2024–25, in the Master’s degree in Physics of Condensed Matter and Biological Systems, coordinated by Prof. Elena del Valle: (I) theory of quantum technologies (E. del Valle), (II) quantum computing (Prof. Eduardo Lee), (III) quantum communication (C. Antón-Solanas):

  1. Photon number statistics
  2. HBT experiment & applications
  3. HOM experiment & applications
  4. Single-photon emission from deterministic sources (I)
  5. Single-photon emission from deterministic sources (II)
  6. Entanglement characterisation & photon gates
  7. Spin–photon entanglement in the solid state

Bibliography: Steck, Quantum and Atom Optics; Grynberg, Aspect & Fabre, Introduction to Quantum Optics; Scully & Zubairy, Quantum Optics; Meystre & Sargent, Elements of Quantum Optics; Cohen-Tannoudji et al., Photons and Atoms; Loudon, The Quantum Theory of Light; Allen & Eberly, Optical Resonance and Two-Level Atoms.

BSc & MSc theses (TFG · TFM)

Contact us if you’d like to do your TFG or TFM on quantum optics experiments — the best moment is during your 3rd (TFG) or 4th (TFM) year. Topics offered every year:

Prácticas externas & research grants

Contact us for “PE curriculares” — with enough time we can design one around your interests. To start research in your 4th year (contact us at the end of the 3rd):

single photons, in pixels

A quantum dot emits one photon per laser pulse. At the beamsplitter it goes one way or the other — never both — so D1 and D2 never click in the same pulse. That is the missing peak at zero delay: g⁽²⁾(0) ≈ 0, the Hanbury Brown–Twiss signature of a single-photon source.

two photons, one beamsplitter

Two photons of random colour enter a 50:50 beamsplitter from different sides. When they are identical (same colour), their paths interfere and they always leave together — D1 and D2 never click at the same time. When they are distinguishable (different colours), each one chooses independently: 25% both transmitted, 25% both reflected, 25% both to D1, 25% both to D2 — so half of the time you get a coincidence. That missing coincidence for identical photons is the Hong–Ou–Mandel effect, our everyday test of photon indistinguishability.

a secret key, photon by photon

BB84, the first quantum key distribution protocol. Alice encodes each random bit in the polarisation of a single photon, choosing at random the rectilinear basis (+: H = 0, V = 1) or the diagonal one (×: D = 0, A = 1). Bob measures each photon in a randomly chosen basis. Then they compare bases in public — never the bits — and keep only the rounds where the bases match: the sifted key. An eavesdropper, Eve, who intercepts a photon must guess the basis too; half of the time she guesses wrong, disturbs the state, and the photon she resends gives Bob the wrong bit with probability 1/2. Intercepting every photon would cause a 25% error rate; here Eve intercepts half of them, so the quantum bit error rate (QBER) jumps from 0% to ~12%, above the ~11% security threshold — Alice and Bob detect her and discard the key. Her footprint is a consequence of the no-cloning theorem.