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Highly Accurate Clock Synchronization

The US Army seeks a partner to license and commercialize a method for synchronizing clocks that are spatially separated
The US Army has conceived and patented an approach to synchronize, with very high accuracy, two real clocks that are spatially separated.  The approach is based on quantum mechanical methods and can provide accuracy significantly beyond that of the Global Positioning System (GPS) and other classical methods in use today. It accomplishes this by overcoming effects due to propagation of reference signals through the Earth’s gravitational field (i.e., curvature of the spacetime continuum).  It is an optical scheme and could benefit any distributed fiber optic network with clock synchronization requirements extending on the order of tens of kilometers.  For example, in communication systems, a more accurate clock enables tighter encryption, which improves security for sending and receiving information throughout the network. 

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a synchronized reference signaling system, a mobile receiver, and a stationary receiver
a synchronized reference signaling system, a mobile receiver, and a stationary receiver
The Technology: 

The US Army Research Laboratory (ARL) is a leader in basic and applied research across the technology spectrum. One of its focus areas is advanced electronic device technologies in support of communications, intelligence, surveillance and reconnaissance.
Time synchronization is accomplished generally by sending reference signals from an accurate and precise master clock.  The reference signals carry a time stamp, which recipients of the reference signals use to synchronize their local clocks with the master clock.  Accuracy provided by a GPS receiver is on the order of nanoseconds (10-9 sec), but there is a growing list of applications, such as coherent detection of electromagnetic signals, where time accuracy needs to be much more precise.  Accounting for curvature of the spacetime continuum is a challenge to achieving very high accuracy.  The ARL method features a simple quantum mechanical algorithm whose accuracy is established by the resolution of the Hong-Ou-Mandel (HOM) interferometer, which has been demonstrated to be 100 femtoseconds (10-13 sec) or better.  The algorithm is based on entangled photon pairs, which allow the synchronization to be carried out over large distances. 

  • Significant increase in accuracy, approaching 10,000x
  • Feasible approach: the main elements have been developed and tested 
  • Useful in fiber optic networks, but could also work in a vacuum via line of sight
  • Diverse markets such as communications, computer networks, navigation, electric grid, astronomy 

The Opportunity: 
  • Issued patent US 7,426,156 is available for license
  • Potential for collaboration with US Army inventor 
  • Essential elements of the ARL system have been experimentally tested; however, these elements have not been combined into an operational system