Coherent light source based on collective spontaneous emission

A coherent light source comprising:

• a chamber for receiving and retaining a group of at least 1000 gaseous state atoms;
• a refrigeration system for cooling the group of atoms to a temperature of less than 100 μK;
• and
• an excitation laser directed into the chamber along a first axis for exciting the group of atoms to an excited state from which they decay to generate a transmitted coherent light;
• wherein the transmitted coherent light is generated by collective spontaneous emission of the group of atoms decaying from excitation from the excitation laser to provide coherent light;
• and
• wherein the group of atoms has a coherent figure of merit of greater than 1, defined as:
• [
• N
• /
• (
• R
• λ
• )
• ]
• 2
• and an incoherent figure of merit less than 1 defined as:
• N
• /
• (
• R
• λ
• )
• 2
• where N is a number of atoms in the group, R is the radial size of the group along the axis of transmitted coherent light, and λ is the wavelength of the transmitted coherent light.