Also known as photonics · optomechanics · cavity QED · bosonic modes · single-photon sources
Photonic and optomechanical systems cover the control of light and of the mechanical motion it couples to:
single-photon sources, optical circuits, cavities, quantum memories and mechanical resonators. Photons rarely
interact, which makes them excellent carriers of quantum information but hard to process. Much of the control
therefore acts on the matter that emits, stores or scatters light, or on the classical settings of optical circuits.
Shaping photons
Emission and absorption. Shaping the drive of an atom in a cavity sets the temporal shape of the emitted
photon. A time-symmetric photon can be absorbed by a second atom with unit probability [1]. An
atom–cavity system driven by an adiabatic Raman transition emits single photons on demand [2]. The
microwave counterpart transferred states between superconducting qubits on different chips
[3]. See State preparation & transfer.
Storage. Electromagnetically induced transparency maps a light pulse onto a collective atomic excitation, the
dark-state polariton, by turning a control field down [4]. The retrieval efficiency of
storage in an atomic ensemble is set by its optical depth or cooperativity, whatever the technique, and optimal
storage strategies follow from this [5]. Time reversal gives optimal input pulse shapes, as
demonstrated in warm rubidium vapour [6].
Quantum dots. Semiconductor quantum dots in photonic nanostructures are bright single-photon sources whose
emission can be engineered [7].
Optical circuits
Any unitary on \(N\) optical modes can be decomposed into beam splitters and phase shifters [8]. A
different mesh design needs half the physical footprint and is more tolerant of losses
[9].
Reconfigurable integrated circuits implement universal linear optics on chip [10]. With single
photons, detectors and feed-forward, linear optics is enough for scalable quantum computation [11, 12]. Setting the phases of such circuits is a static control and calibration problem. Continuous-variable
optics with squeezing and nonlinearities is covered in Bosonic & continuous-variable control and Linear quantum systems & coherent feedback.
Optomechanics
Radiation pressure couples light to the motion of mechanical resonators [13].
Sideband cooling brought micromechanical and nanomechanical oscillators to their quantum ground state
[14, 15]. Optically levitated nanoparticles have been cooled to the ground
state with a cavity [16], and with measurement-based feedback, both at room temperature
[17] and in cryogenic free space [18]. Measurement-based control has
also cooled membrane resonators [19]. See Measurement-based feedback and Control of open quantum systems.
Limitations
Photon loss is the dominant error, and loss in sources, circuits and detectors compounds.
Probabilistic sources and gates need multiplexing or feed-forward, which require fast, low-latency control.
Mechanical resonators couple strongly to their thermal environment, so control must outpace thermal decoherence.
Key papers
J. I. Cirac, P. Zoller, H. J. Kimble and H. MabuchiQuantum State Transfer and Entanglement Distribution among Distant Nodes in a Quantum NetworkPhys. Rev. Lett.78, 3221-3224 (1997)doi
Shaped laser pulses map an atom's state onto a photon that a distant atom absorbs with unit probability.
Michael Reck, Anton Zeilinger, Herbert J. Bernstein and Philip BertaniExperimental realization of any discrete unitary operatorPhys. Rev. Lett.73, 58-61 (1994)doi
Any discrete unitary on optical modes can be built from beam splitters and phase shifters.
Irina Novikova, Alexey V. Gorshkov, David F. Phillips, Anders S. Sørensen, Mikhail D. Lukin and Ronald L. WalsworthOptimal Control of Light Pulse Storage and RetrievalPhys. Rev. Lett.98, 243602 (2007)doi
Optimal input pulse shapes for light storage, found by time reversal and demonstrated in warm vapour.
Markus Aspelmeyer, Tobias J. Kippenberg and Florian MarquardtCavity optomechanicsRev. Mod. Phys.86, 1391-1452 (2014)doi
Review of cavity optomechanics — radiation-pressure coupling, cooling and quantum control of motion.
Lorenzo Magrini, Philipp Rosenzweig, Constanze Bach, Andreas Deutschmann-Olek, Sebastian G. Hofer, et al.Real-time optimal quantum control of mechanical motion at room temperatureNature595, 373-377 (2021)doi
Measurement-based optimal feedback cools a levitated nanoparticle to its motional ground state at room temperature.
Pieter Kok, W. J. Munro, Kae Nemoto, T. C. Ralph, Jonathan P. Dowling and G. J. MilburnLinear optical quantum computing with photonic qubitsRev. Mod. Phys.79, 135-174 (2007)doi
Review of linear-optical quantum computing with photonic qubits.
References
J. I. Cirac, P. Zoller, H. J. Kimble and H. MabuchiQuantum State Transfer and Entanglement Distribution among Distant Nodes in a Quantum NetworkPhys. Rev. Lett.78, 3221-3224 (1997)doi
Axel Kuhn, Markus Hennrich and Gerhard RempeDeterministic Single-Photon Source for Distributed Quantum NetworkingPhys. Rev. Lett.89, 067901 (2002)doi
P. Kurpiers, P. Magnard, T. Walter, B. Royer, M. Pechal, et al.Deterministic quantum state transfer and remote entanglement using microwave photonsNature558, 264-267 (2018)doi
M. Fleischhauer and M. D. LukinDark-State Polaritons in Electromagnetically Induced TransparencyPhys. Rev. Lett.84, 5094-5097 (2000)doi
Alexey V. Gorshkov, Axel André, Mikhail D. Lukin and Anders S. SørensenPhoton storage in-Λ-type optically dense atomic media. I. Cavity modelPhys. Rev. A76, 033804 (2007)doi
Irina Novikova, Alexey V. Gorshkov, David F. Phillips, Anders S. Sørensen, Mikhail D. Lukin and Ronald L. WalsworthOptimal Control of Light Pulse Storage and RetrievalPhys. Rev. Lett.98, 243602 (2007)doi
Peter Lodahl, Sahand Mahmoodian and Søren StobbeInterfacing single photons and single quantum dots with photonic nanostructuresRev. Mod. Phys.87, 347-400 (2015)doi
Michael Reck, Anton Zeilinger, Herbert J. Bernstein and Philip BertaniExperimental realization of any discrete unitary operatorPhys. Rev. Lett.73, 58-61 (1994)doi
William R. Clements, Peter C. Humphreys, Benjamin J. Metcalf, W. Steven Kolthammer and Ian A. WalsmleyOptimal design for universal multiport interferometersOptica3, 1460 (2016)doi
Jacques Carolan, Christopher Harrold, Chris Sparrow, Enrique Martín-López, Nicholas J. Russell, et al.Universal linear opticsScience349, 711-716 (2015)doi
E. Knill, R. Laflamme and G. J. MilburnA scheme for efficient quantum computation with linear opticsNature409, 46-52 (2001)doi
Pieter Kok, W. J. Munro, Kae Nemoto, T. C. Ralph, Jonathan P. Dowling and G. J. MilburnLinear optical quantum computing with photonic qubitsRev. Mod. Phys.79, 135-174 (2007)doi
Markus Aspelmeyer, Tobias J. Kippenberg and Florian MarquardtCavity optomechanicsRev. Mod. Phys.86, 1391-1452 (2014)doi
J. D. Teufel, T. Donner, Dale Li, J. W. Harlow, M. S. Allman, et al.Sideband cooling of micromechanical motion to the quantum ground stateNature475, 359-363 (2011)doi
Jasper Chan, T. P. Mayer Alegre, Amir H. Safavi-Naeini, Jeff T. Hill, Alex Krause, et al.Laser cooling of a nanomechanical oscillator into its quantum ground stateNature478, 89-92 (2011)doi
Uroš Delić, Manuel Reisenbauer, Kahan Dare, David Grass, Vladan Vuletić, et al.Cooling of a levitated nanoparticle to the motional quantum ground stateScience367, 892-895 (2020)doi
Lorenzo Magrini, Philipp Rosenzweig, Constanze Bach, Andreas Deutschmann-Olek, Sebastian G. Hofer, et al.Real-time optimal quantum control of mechanical motion at room temperatureNature595, 373-377 (2021)doi
Felix Tebbenjohanns, M. Luisa Mattana, Massimiliano Rossi, Martin Frimmer and Lukas NovotnyQuantum control of a nanoparticle optically levitated in cryogenic free spaceNature595, 378-382 (2021)doi
Massimiliano Rossi, David Mason, Junxin Chen, Yeghishe Tsaturyan and Albert SchliesserMeasurement-based quantum control of mechanical motionNature563, 53-58 (2018)doi
Recent papers
1,072 tracked papers since 2000 are classified
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Programmable preparation of entangled quantum states is a central requirement for scalable quantum information processing, quantum networking and photonic quantum computing. Topological photonic platforms offer an attractive route towards robust quantum-state generation by encoding information in symmetry- protected optical modes, yet the generated entangled states are typically dictated by the lattice geometry and therefore lack programmability. Here we demonstrate programmable preparation of topological entangled states by inverse engineering the nonlinear optical pump profile of an integrated photonic lattice. Our approach enables deterministic control over both the dimensionality and modal structure of the generated entangled state while preserving its topological character. We experimentally realize silicon photonic topological superlattices in which the nonlinear generation pathway itself becomes programmable via tailored excitations. The superlattices host a multiband manifold of co localized topological interface modes, while coherently controlled inputs synthesize pump superpositions within this protected basis. We showcase this principle by selectively addressing topological biphoton eigenstates, steering correlations to produce a desired target state in a high-dimensional Hilbert space, and inverse-designing pump states that generate targeted Schmidt dimensionalities. Site-resolved two-photon correlation measurements remain reproducible across nominally identical fabricated devices, demonstrating robustness to realistic nanofabrication-induced disorder. Programmable preparation of topological entangled states establishes a pathway towards exploiting topological photonic modes as application-specific quantum resources, enabling tailored input states for high-dimensional quantum communication, quantum networking and photonic quantum computing.
Fault tolerant quantum computers greatly benefit from having both high fidelity entangling gates and a non-local qubit connectivity. However, most entangling gates for neutral atoms are local, requiring separated atoms to be moved using optical tweezers to yield entanglement between them. Here, we design a high fidelity Mølmer Sørensen-like entangling gate between neutral atoms coupled to a photonic cavity, enabling a programmable all-to-all connectivity through the shared cavity coupling. The gate is both robust to changes in cavity photon number, and enables selective entanglement between any subset of separated atoms through local laser addressing. This eliminates the need to physically move atoms to perform the gate, and therefore motional errors and erasure are suppressed. Using experimentally realistic parameters we demonstrate gate fidelities exceeding $F > 0.99$, with higher fidelities achievable through optimal control of the pump amplitudes.
Time-domain multiplexing of continuous-variable quantum states provides a scalable approach to photonic quantum information processing, in which individual temporal modes can be sequentially manipulated within a common optical path. Here we demonstrate pulse-resolved post-generation phase control of squeezed-vacuum states at a repetition rate of 93 MHz using a low-loss bulk lithium-niobate electro-optic modulator driven by a broadband RF power amplifier. The driving architecture exploits low-cost, commercially available RF components and the impedance mismatch between the RF chain and the capacitive crystal load, rather than relying on dedicated custom high-voltage electronics, to obtain large voltage excursions on the modulator while operating above the piezoelectric-resonance region of lithium niobate. The modulator is driven synchronously with the optical pulse train, enabling the phase of consecutive temporal modes to be individually controlled. An interferometric calibration yields a maximum differential phase excursion of 1.93 rad. We apply the modulator to a 1035 nm squeezed-vacuum field generated by a synchronously pumped optical parametric oscillator and characterize the output using time-resolved balanced homodyne detection. With the local-oscillator phase kept fixed, the phase of the squeezed state is varied from pulse to pulse, and the corresponding phase-dependent quadrature variance is reconstructed. The resulting quadrature scan agrees with an equivalent measurement obtained by varying the local-oscillator phase with a piezoelectric actuator. These results demonstrate post-generation quantum-state phase control at the individual-pulse level and provide an electro-optic building block for programmable manipulation of time-multiplexed quantum states in recirculating optical architectures.
Bending the axis of a mode-evolution coupler suppresses the nonadiabatic coupling between its supermodes, and bent couplers of this kind were recently shown to realize the counter-diabatic (CD) protocol. Here we identify the operator responsible. Rigid lateral displacement of a waveguide structure is generated by the transverse momentum $\hat p_x$, whose diagonal matrix elements vanish in a real supermode basis and whose off-diagonal element is purely imaginary; in a two-mode system such an operator is proportional to $\sy$. The CD term of a two-waveguide coupler is itself proportional to $\sy$, while the detuning and the coupling, the two parameters set by the waveguide widths and spacing, lie in the $σ_z$--$σ_x$ plane and cannot produce it. The transverse momentum is therefore the CD generator of the bent coupler, by necessity rather than by design. Equating the term it supplies to the nonadiabatic coupling gives the axis slope in closed form as a ratio of two matrix elements of the unperturbed supermodes at a single cross section, which a commutator identity recasts in coupled-mode variables as $\dot{\xo}=\dotθ/(γ\dbeta^{2})$. The expression agrees with the numerical offset search to $0.3\%$ and requires no search. Beam propagation simulations confirm the design and compare it, for the first time, with the CD protocol realized by unitary transformation in a straight coupler built from the same reference structure. The two devices reach $0.994$ and $1.000$ supermode fidelity where the untreated coupler reaches $0.886$, and agree in bandwidth and fabrication tolerance, while their internal trajectories differ by exactly the frame transformation that relates them.
Bound states in the continuum (BICs) provide a mechanism for preserving entanglement in waveguide quantum electrodynamics. Here, using quantum control techniques in a configuration of two braided giant atoms, we propose a robust approach to create high-fidelity entangled BICs. The protocol combines quasi-Floquet modulation of the effective atom--waveguide couplings with an independent phase-controlled atomic exchange, which provides restricted counterdiabatic assistance for preparing the complete dressed BIC. In the lossless effective model, we obtain a full-state BIC fidelity of $0.99992$ and an unconditional atomic Bell fidelity of $0.99588$ using a fast control protocol. Microscopic finite-mode simulations validate the central-sideband description during the passage, while static calibration-error scans quantify its control tolerances. A separate microscopic study with relaxation and dephasing, using experimentally motivated component scales, identifies a finite useful entanglement window and a benefit from shaping the coupling envelopes. These results support controlled preparation, retention, and retrieval of dressed entanglement within the stated control and noise assumptions.