Molecular Atomic Clock With Wave Propagating Rotational Spectroscopy Cell

Abstract

In an example, an apparatus comprises a sealed container containing a dipolar gas. The apparatus also comprises a first transmit antenna, a second transmit antenna, and a receive antenna each communicatively coupled to the sealed container. The apparatus also comprises a control circuit including a transceiver, the control circuit having a first transmit output, a second transmit output, and a receive input, the first transmit output coupled to the first transmit antenna, the second transmit output coupled to the second transmit antenna, and the receive input coupled to the receive antenna.

What is claimed is: 
     
         1 . An apparatus comprising:
 a sealed container containing a dipolar gas;   a first transmit antenna, a second transmit antenna, and a receive antenna each communicatively coupled to the sealed container; and   a control circuit including a transceiver, the control circuit having a first transmit output, a second transmit output, and a receive input, the first transmit output coupled to the first transmit antenna, the second transmit output coupled to the second transmit antenna, and the receive input coupled to the receive antenna.   
     
     
         2 . The apparatus of  claim 1 , wherein the control circuit is configured to provide a first signal at the first transmit output, and provide a second signal at the second transmit output; and
 wherein the first transmit antenna is configured to transmit the first signal in the sealed container in a first direction, and the second transmit antenna is configured to transmit the second signal in the sealed container in a second direction opposite to the first direction.   
     
     
         3 . The apparatus of  claim 1 , wherein the control circuit includes a bi-directional coupler having a coupler input, a first coupler output, and a second coupler output, the first coupler output coupled to the first transmit output, and the second coupler output coupled to the second transmit output; and
 wherein the transceiver includes:
 a signal generator having a first output, a reference clock output, and a control input, the first output coupled to the coupler input; and 
 a lock in amplifier having an amplifier input and an amplifier output, the amplifier input coupled to the receive input, and the amplifier output coupled to the control input. 
   
     
     
         4 . The apparatus of  claim 3 , wherein the control input is a first control input, the amplifier input is a first amplifier input, the signal generator has a second control input, the lock in amplifier has a second amplifier input, and the control circuit includes a modulator having a first modulator output coupled to the second control input and a second modulator output coupled to the second amplifier input. 
     
     
         5 . The apparatus of  claim 4 , further comprising an error processing circuit coupled between the amplifier output and the first control input. 
     
     
         6 . The apparatus of  claim 5 , wherein the error processing circuit includes at least one of: a filter, or a proportional integral derivative (PID) circuit. 
     
     
         7 . The apparatus of  claim 3 , wherein the bi-directional coupler includes a pair of coupled conductors. 
     
     
         8 . The apparatus of  claim 3 , wherein the bi-directional coupler includes a sidewall aperture coupler. 
     
     
         9 . The apparatus of  claim 3 , wherein the bi-directional coupler is configured to:
 receive a first signal at the coupler input;   provide the first signal at the first coupler output; and   provide a second signal as an attenuated version of the first signal at the second coupler output.   
     
     
         10 . The apparatus of  claim 1 , wherein the control circuit has a clock output. 
     
     
         11 . The apparatus of  claim 1 , wherein the control circuit is configured to:
 provide a first signal at the first transmit output;   provide a second signal at the second transmit output;   receive a third signal at the receive input;   determine, based on the third signal, a first frequency of a first peak absorption of the first and second signals by the dipolar gas;   determine, based on the third signal, a second frequency of a second peak absorption of the first and second signals by the dipolar gas;   determine a third frequency based on the first and second frequencies; and   provide a fourth signal having the third frequency at the clock output.   
     
     
         12 . The apparatus of  claim 1 , wherein the sealed container has a longitudinal portion and a branch portion. 
     
     
         13 . The apparatus of  claim 12 , wherein the first transmit antenna is communicatively coupled to the branch portion, and the second transmit antenna and the receive antenna are communicatively coupled to the longitudinal portion. 
     
     
         14 . The apparatus of  claim 12 , wherein the first and second transmit antennas are communicatively coupled to the longitudinal portion, and the receive antenna is communicatively coupled to the branch portion. 
     
     
         15 . The apparatus of  claim 12 , wherein the branch portion is a first branch portion, and the sealed container has a second branch portion, the first and second branch portions extending towards opposite sides of the longitudinal portion. 
     
     
         16 . The apparatus of  claim 15 , wherein the first transmit antenna is communicatively coupled to the longitudinal portion, the second transmit antenna is communicatively coupled to the first branch portion, and the receive antenna is communicatively coupled to the second branch portion. 
     
     
         17 . The apparatus of  claim 1 , wherein the sealed container has a circular portion, a first branch portion, a second branch portion, and a third branch portion; and
 wherein the first transmit antenna, the second transmit antenna, and the receive antenna are communicatively coupled to, respectively, the first branch portion, the second branch portion, and the third branch portion.   
     
     
         18 . The apparatus of  claim 17 , wherein the control circuit is configured to provide a first signal at the first transmit output, and provide a second signal at the second transmit output, the first and second signals having a particular wavelength when propagating in the dipolar gas; and
 wherein a diameter of the circular portion is based on the wavelength.   
     
     
         19 . An apparatus comprising:
 a sealed container containing a dipolar gas, the sealed container having a branch portion and a longitudinal portion;   a transmit antenna communicatively coupled to a first end of the longitudinal portion;   a receive antenna communicatively coupled to the branch portion; and   an electromagnetic reflector at a second end of the longitudinal portion, the second end being opposite to the first end; and   a control circuit including a transceiver, the control circuit having a transmit output and a receive input, the transmit output coupled to the transmit antenna, and the receive input coupled to the receive antenna.   
     
     
         20 . An apparatus comprising:
 a sealed container containing a dipolar gas, the sealed container having a circular portion, a first branch portion, and a second branch portion;   a transmit antenna communicatively coupled to the first branch portion;   a receive antenna communicatively coupled to the second branch portion; and   a control circuit including a transceiver, the control circuit having a transmit output and a receive input, the transmit output coupled to the transmit antenna, and the receive input coupled to the receive antenna.   
     
     
         21 . The apparatus of  claim 20 , wherein the control circuit is configured to provide a signal at the transmit output, the signal having a particular wavelength when propagating in the dipolar gas; and
 wherein a diameter of the circular portion is based on the wavelength.