Electrically Tunable Quantum Emitter Devices

• Electrically tunable quantum emitter devices are integrated solid-state photonic systems where external electrical signals dynamically control optical transitions and emission characteristics using mechanisms like QCSE and electro-optic modulation.
• These devices leverage diverse material platforms such as III–V quantum dots, 2D van der Waals materials, and hybrid photonic structures to achieve high photon purity, fast modulation, and precise spectral tuning.
• Key tuning methods—including electric field control, electromechanical actuation, and gate-based charge manipulation—enable deterministic single-photon generation, on-demand waveform shaping, and robust quantum transduction.

Electrically tunable quantum emitter devices are integrated solid-state photonic systems in which the optical transition energy, coupling strength, and emission characteristics of a quantum emitter can be dynamically and reversibly controlled by the application of external electrical signals. Such tunability enables spectral matching among multiple quantum light sources, reconfigurable single-photon emission, quantum transduction, and active manipulation of photon waveforms, which are pivotal for scalable quantum networks and photonic quantum information processing. Devices span a diverse materials landscape: III–V self-assembled quantum dots, rare-earth ions in oxides, color centers in 2D van der Waals materials, and molecular emitters in hybrid nanostructures. Electrical control is achieved via the quantum-confined Stark effect, electro-optic index modulation, field-tunable charge state manipulation, and electromechanical actuation, among other mechanisms.

1. Device Architectures and Materials Platforms

Electrically tunable quantum emitter devices appear in several architectures:

1.1 III–V Quantum Dot (QD) Heterostructures:

Semiconductor quantum dots are embedded in diode stacks enabling precise vertical or lateral electric field tuning. For instance, InGaAs or InAs QDs are incorporated into p–i–n or n^{++}–i–n^{+} structures to exploit the quantum-confined Stark effect (QCSE) for emission energy control, with electrical isolation implemented via dielectric (e.g., SiO₂/Al₂O₃) or all-epitaxial barriers (Lee et al., 2017, Aghaeimeibodi et al., 2018, Martin et al., 9 Jun 2025). Nanomembrane, nanowire, and bullseye (circular photonic crystal) geometries enable integration with high-efficiency cavity or grating structures (Wijitpatima et al., 12 Jun 2024, Barbiero et al., 16 May 2025, Kremer et al., 2014).

1.2 Lithium Niobate on Insulator (LNOI):

Rare-earth ion (REI: e.g., Yb³⁺) quantum emitters are implanted into thin-film lithium niobate microdisks, with microcavities and electrodes fabricated atop LNOI wafers. The Pockels effect in lithium niobate allows ultrafast resonance tuning via applied voltage, enabling direct modulation of the REI emission environment (Xia et al., 2021).

1.3 2D Materials and van der Waals Heterostructures:

Atomic defects in hexagonal boron nitride (h-BN), interlayer excitons in WSe₂, or molecular emitters near 2D electrodes form the active medium for field-modulated emission. Devices leverage atomically thin electrodes (graphene, MoS₂, carbon nanotubes) and high-quality encapsulation for low-noise operation (Noh et al., 2018, Almutlaq et al., 2023, Ripin et al., 2023, Schädler et al., 2019).

1.4 Hybrid-Integrated Photonic Platforms:

Hybrid approaches combine III–V microchiplets containing QDs with mature silicon photonic circuits using transfer printing or adhesive bonding. Each emitter can be individually tuned via local charge-memory effects or built-in gates, enabling wavelength-programmable quantum photonic circuits at wafer scale (Larocque et al., 2023, Salamon et al., 6 Aug 2025).

2. Electrical Tuning Mechanisms

2.1 Quantum-Confined Stark Effect (QCSE):

A vertical or lateral electric field F applied across a quantum dot modifies the optical transition energy E via

$\Delta E(F) = -pF + \frac{1}{2}\beta F^2$

where p is the permanent dipole moment (∼0.05–1 e·nm for III–V QDs, 0.1–1 Debye for color centers), and β is the polarizability (typical values −1 to −10 μeV/(kV/cm)²) (Martin et al., 9 Jun 2025, Aghaeimeibodi et al., 2018, Kremer et al., 2014, Zhang et al., 2016). Tuning ranges >5 nm in III–V QDs and >10 meV in GaN/AlN nanowires are reported (Barbiero et al., 16 May 2025, Spies et al., 2020).

2.2 Electro-Optic/Pockels Tuning:

Microcavities constructed from LN or other electro-optic materials offer direct modulation of resonance frequency via refractive index changes,

$\Delta \omega_c(V) \approx \frac{d\omega_c}{dV} V$

with tuning rates ≈270 MHz/V and total tuning spans up to 160 GHz achieved with <300 V in LNOI devices (Xia et al., 2021).

2.3 Electric Field Tuning of Exciton-Phonon/Polaron Couplings:

In bilayer WSe₂, the out-of-plane field modifies the interlayer exciton (IX) separation and thus the exciton–phonon (breathing mode) coupling strength,

$g(E) = g_0 + eEx_{\mathrm{zpf}}$

Nonlinear tuning of the Huang–Rhys factor S and the phonon-coupling rate g(E) beyond 1 meV is demonstrated (Ripin et al., 2023).

2.4 Charge State and Spin State Manipulation:

Gate voltages modulate occupation in QDs as well as charge state and trion/biexciton transitions in van der Waals monolayers, with charge-confinement radii as small as ≈10 nm feasible using 1-nm diameter CNT gates (Almutlaq et al., 2023).

2.5 Electromechanical (MEMS/NEMS) Tuning:

Electrostatic actuation of mechanically suspended nanobeams or cantilevers enables direct tuning of photonic crystal cavity resonances by modifying physical gap or index overlap, yielding tuning up to >1.8 nm in integrated PhC cavities (Brunswick et al., 12 Mar 2025, Petruzzella et al., 2017).

3. Key Performance Figures and Device Metrics

Device type	Tuning range	Switching time	Quantum metrics
LNOI REI cavity (Xia et al., 2021)	160 GHz (162 GHz)	5 μs (200 kHz bw)	Purcell F_P ≈ 7.6–20
InP QDs (C-band) (Martin et al., 9 Jun 2025)	>2.4 nm (>1.2 meV)	ns–μs	g^{(2)}(0) ≈ 0.04, FSS tun.
InGaAs QDs (GaAs) (Aghaeimeibodi et al., 2018)	5.1 meV (8 nm)	ns–μs	g^{(2)}(0) ≈ 0.12–0.31
h-BN defects (Noh et al., 2018)	5.4 nm/GV/m (up to 0.6 GV/m)	ms–μs	g^{(2)}(0) < 0.5, RT opt.
Monolayer WSe₂ (Almutlaq et al., 2023)	3–8 meV (trion splitting)	ms–μs	>20 meV trion binding E_b^T
GaN nanowire QDs (Spies et al., 2020)	~100 meV over 5 V	10–100 MHz	Charged/neutral tuning
Bullseye O-band QDs (Barbiero et al., 16 May 2025)	>10 nm (7 meV)	–	g^{(2)}(0) = 0.107, F_P~2.4
CBG PIN-diode QDs (Wijitpatima et al., 12 Jun 2024)	0.7 meV (0.4 nm)	–	Purity ≥99%, PEE >30%
Bilayer WSe₂ (Ripin et al., 2023)	ZPL ≥6 meV, S up to 6	ms–μs	Single-phonon Fock states

High single-photon purity [g^{(2)}(0) < 0.01–0.1], lifetimes from hundreds of ns (REI) to sub-ns (QDs), extraction efficiency >30%, and indistinguishability up to >90% (with resonant or post-selected protocols) are achieved in optimized geometries (Wijitpatima et al., 12 Jun 2024, Barbiero et al., 16 May 2025, Schall et al., 2021). Fast modulation (μs–ns) and on-demand waveform shaping (via electro-optic or MEMS) permit deterministic and reconfigurable single-photon generation (Xia et al., 2021, Brunswick et al., 12 Mar 2025).

4. Hybrid, Large-Scale, and Wafer-Scale Integration

Hybrid integration with silicon photonics via transfer-printing (InP/SOI), die-to-die bonding (GaAs/SiN), or direct epitaxial growth (III–V/Si) enables electrical control of multiple quantum emitters on advanced photonic integrated circuits (Larocque et al., 2023, Salamon et al., 6 Aug 2025). Individual wavelength programmability is accomplished using local charge-trapping memories or individually addressed gates. Demonstrated architectures support crosstalk ≤1% at 5 μm pitch, tuning ranges ≥60 GHz, and stable retention over hours at 5 K; on-chip single-photon rates of >10⁶ s⁻¹ at <200 MHz pulse rates are routine for high extraction efficiency chiplets (Larocque et al., 2023, Wijitpatima et al., 12 Jun 2024).

In 2D materials, sub-15 nm lateral addressability using 1 nm CNT gates provides a pathway to large arrays of electrically controlled emitters, enabling charged biexciton and trion emission with gate-defined spatial confinement at the exciton Bohr radius limit (Almutlaq et al., 2023).

5. Quantum Photonic Applications and Protocols

Electrically tunable quantum emitter devices underpin a suite of quantum photonic applications:

5.1 Deterministic On-Demand Single-Photon Sources:

Active electrical control allows spectral alignment and deterministic triggering, supporting high-purity and high-indistinguishability photon generation—required for photonic boson sampling, all-photonic repeaters, and quantum key distribution (Lee et al., 2017, Wijitpatima et al., 12 Jun 2024, Martin et al., 9 Jun 2025).

5.2 Spectral-Temporal-Spatial Multiplexing:

Multi-knob electrical tuning (Stark effect, electro-optic modulation, electromechanical actuation) enables spectral and temporal multiplexing with μs switching—supporting scalable quantum repeater networks and quantum information multiplexing (Xia et al., 2021, Brunswick et al., 12 Mar 2025).

5.3 Quantum Transduction and Cavity QED:

Voltage-tunable exciton–phonon coupling (S > 6) and phonon Fock-state heralding offer a robust platform for photon–phonon quantum transduction and hybrid entanglement generation (Ripin et al., 2023). Cavity–emitter resonance matching via electrical tuning achieves Purcell enhancement for efficient photon extraction and waveform engineering (Brunswick et al., 12 Mar 2025, Xia et al., 2021).

5.4 Spin-Photon Interfaces and Entanglement Sources:

Gate-tunable excitonic and trionic transitions in atomically thin semiconductors (MoS₂, WSe₂) and semiconductor QDs enable electrical control of emission charge state and FSS tuning for entangled-photon pair emission or spin-photon conversion (Almutlaq et al., 2023, Zhang et al., 2016).

6. Fabrication, Stability and Trade-Offs

6.1 Fabrication Approaches:

Deterministic QD placement combines low-temperature cathodoluminescence mapping, electron beam lithography, and aligned patterning of photonic structures (CBG, bullseye, PhC, nanowire). Hybrid integration via transfer-printing or adhesive bonding onto Si/SiN is fully CMOS compatible (Wijitpatima et al., 12 Jun 2024, Larocque et al., 2023, Salamon et al., 6 Aug 2025). Van der Waals assembly provides pick-and-place stacking for 2D materials (Noh et al., 2018, Ripin et al., 2023).

6.2 Trade-Offs and Optimization:

• Electrical isolation for wide tuning competes with carrier injection and out-coupling (e.g. thin oxide vs. conductive transparent contacts).
• High field bias can induce carrier tunneling, reducing emission intensity and increasing linewidth by leakage (Aghaeimeibodi et al., 2018, Spies et al., 2020).
• Ridge/contact geometry in CBG and bullseye cavities balances photon extraction efficiency and series resistance (Wijitpatima et al., 12 Jun 2024).
• Piezoelectric versus electric field tuning: strain provides reversible, low-noise tuning (up to ~1 meV), while electric fields achieve >10 meV but can introduce charge noise unless contacts and interfaces are optimized (Kremer et al., 2014, Zhang et al., 2016).

6.3 Long-Term Stability:

Electrostatic tuning shows minimal hysteresis, drift <50 pm over minutes (4 K). Non-volatile photonic memory retains settings over hours with crosstalk below 1% in hybrid architectures (Larocque et al., 2023, Wijitpatima et al., 12 Jun 2024).

7. Outlook and Future Directions

Electrically tunable quantum emitter devices have reached key performance benchmarks necessary for integration into multi-source quantum photonic networks: fast, reversible, broad tuning; high extraction and purity; and compatibility with wafer-scale silicon photonics and dense 2D material integration. Key future directions include:

• Extension of electrical tuning to telecom C-band quantum dots for direct fiber-network integration (Martin et al., 9 Jun 2025, Barbiero et al., 16 May 2025).
• Fully CMOS-compliant scaling using transfer printing, cross-bar gating architectures, and photonic circuit layout for thousands of independently tunable emitters (Larocque et al., 2023).
• Integration of voltage-controlled quantum emitter devices with photonic and phononic cavities for strong-coupling cavity QED and quantum transduction (Ripin et al., 2023, Xia et al., 2021).
• Development of deterministic multi-emitter entanglement and cluster-state on-chip photonic sources via addressable QDM and coupled QD cavity networks (Schall et al., 2021, Wijitpatima et al., 12 Jun 2024).
• Exploitation of ultra-fast on-chip electrical modulation bandwidths (GHz regime) and combined fast electro-optic and MEMS tuning for waveform control, time-bin encoding, and ultrafast photon gates (Brunswick et al., 12 Mar 2025, Xia et al., 2021).

Electrically tunable quantum emitter devices form the backbone of reconfigurable, large-scale quantum photonic architectures, meeting the requirements for next-generation quantum information, communication, and sensing systems.