Terahertz heterodyne receiver based on a quantum cascade laser and a superconducting bolometer

We report the first demonstration of an all solid-state heterodyne receiver that can be used for high-resolution spectroscopy above $2\mathrm{THz}$ suitable for space-based observatories. The receiver uses a NbN superconducting hot-electron bolometer as mixer and a quantum cascade laser operating at $2.8\mathrm{THz}$ as local oscillator. We measure a double sideband receiver noise temperature of $1400\mathrm{K}$ at $2.8\mathrm{THz}$ and $4.2\mathrm{K}$ , and find that the free-running QCL has sufficient power stability for a practical receiver, demonstrating an unprecedented combination of sensitivity and stability.