Answer: 55 years.
Donna Strickland, a scientist from the University of Waterloo in Canada, recently became the third woman in history to win a Nobel Prize in Physics, and the first to do so in more than five decades. She won alongside Gérard Mourou from École Polytechnique in France and Arthur Ashkin from Bell Labs in the U.S. for their work with lasers.
Strickland and Mourou jointly won half of the prize for developing a new amplification procedure for high-intensity laser pulses called chirped-pulse amplification. The two scientists devised a way to amplify short laser pulses without damaging the material used to do so or resorting to larger, more expensive lasers and equipment.
The other half of the prize recognized Ashkin for using lasers to develop optical tweezers for moving microscopic objects like molecules.
Previous female winners in physics include Maria Goeppert Mayer (1963) and Marie Curie (1903).