Lasers for Quantum Photonics
Author: the photonics expert Dr. Rüdiger Paschotta
Definition: lasers which are specifically suitable for applications in quantum photonics
More general term: lasers
Categories: laser devices and laser physics, quantum optics
DOI: 10.61835/o2n Cite the article: BibTex plain textHTML Link to this page LinkedIn
Various types of lasers are needed for specific purposes in quantum photonics. Often they have to meet quite special requirements. Some examples are given in the following sections.
Application Areas
Lasers as Pump Sources for Single-photon or Photon Pair Emitters
Single-photon emitters, as needed e.g. in quantum communications, are generally no lasers (even when containing a light emitter in an optical resonator). However, some of them (e.g. based on quantum dots) require a pulsed laser (e.g. a picosecond laser) as a pump source. Such a laser must provide a short light pulse with low pulse energy, preferably with a reasonable efficiency, i.e., with very low power consumption, and high beam quality. Often it also needs to emit in a special wavelength range. Laser diodes are frequently used.
For the generation of entangled photon pairs in nonlinear crystal materials, one also requires a pump laser. The demands can be very different depending on the concrete case, for example concerning pulsed or continuous-wave operation, optical power or pulse energy, emission wavelength, etc. Frequently, a short emission wavelength, a narrow linewidth and a high beam quality are required.
Lasers for Manipulating and Readout of Quantum Bits
Quantum bits (qbits) are often manipulated (e.g. initialized) and/or read with laser pulses. Essential requirements for the laser are usually a special emission wavelength and a small linewidth, as well as precise control of the timing and energy of the pulses.
Lasers for Trapping and Cooling of Atoms and Ions
Lasers are used for optical traps, capturing multiple atoms or ions, or sometimes a single atom or ion. Such atoms or ions can be used to represent quantum states. This often requires continuous wave operation of the laser(s) at a specific wavelength and with a low linewidth. Depending on the circumstances, the required optical power can be considerable.
Spectroscopy in Quantum Sensing and Metrology
Ultra-stable lasers with very low laser noise, a narrow linewidth, and possibly some wavelength tuning are used for precision spectroscopy in quantum sensing devices, where photon entanglement, single photons, or squeezed states of light are used for extremely precise measurements.
In some cases, a frequency comb from a accurately stabilized mode-locked laser is required instead of a single-frequency output. There are several powerful methods of frequency comb spectroscopy.
Indirect Uses
Lasers can also find various indirect uses for quantum photonics, e.g. for the fabrication of photonic integrated circuits by ultrashort pulse laser material processing
Typical Requirements
Some typical requirements for such lasers, as already mentioned above, are:
- special emission wavelengths, which are often not accessible by common laser gain media
- narrow linewidth
- very low laser noise and high beam quality
More to Learn
Encyclopedia articles:
Suppliers
The RP Photonics Buyer's Guide contains seven suppliers for lasers for quantum photonics. Among them:
TOPTICA Photonics
TOPTICA's products provide an ultra-broad laser wavelength coverage: 190 nm – 0.1 THz (corresponding to 3 mm). They enable a big variety of demanding applications in quantum optics, spectroscopy, biophotonics, microscopy, test & measurement, as well as materials inspection.
all wavelengths. From 190 nm to 0.1 THz
HÜBNER Photonics
The realization of quantum-sensor based experimental setups and products relies on the availability of state-of-the art components like specialized diamond tips, fast low-noise electronics, and high-performance lasers. At HÜBNER Photonics we offer the following lasers targeted at quantum applications:
- The Cobolt 06-01 Series contains lasers over a large wavelength range in a compact plug and play format. The Series consists of high-performance fixed wavelength diode laser modules (MLD) and diode-pumped lasers (DPL). High speed direct modulation capability and true off during modulation make them ideal for applications in bioimaging and quantum technologies.
- The C-WAVE is also used to test the quality of artificially grown structures with color centers designed for quantum applications. Key characteristics of the C-WAVE are the wide spectral coverage in the visible and NIR (450 nm – 3.5 µm), narrow linewidth (< 1 MHz), mode-hop-free tunability, high output power of several hundred milliwatts, and its nearly perfect Gaussian beam profile.
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