Picosecond

{{Short description|One trillionth of a second}}

{{Infobox unit

| name = picosecond

| image =

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| symbol = ps

| standard = SI

| quantity = time

| units1 = SI units

| inunits1 = {{val|e=-12|ul=s}}

}}

A picosecond (abbreviated as ps) is a unit of time in the International System of Units (SI) equal to 10⁻¹² or {{frac|1|1 000 000 000 000}} (one trillionth) of a second. That is one trillionth, or one millionth of one millionth of a second, or 0.000 000 000 001 seconds.

A picosecond is to one second, as one second is to approximately 31,688.76 years.

Multiple technical approaches achieve imaging within single-digit picoseconds: for example, the streak camera or intensified CCD (ICCD) cameras are able to picture the motion of light.{{cite web|url=http://web.mit.edu/newsoffice/2011/trillion-fps-camera-1213.html|title=Trillion-frame-per-second video|publisher=Massachusetts Institute of Technology|access-date=2014-03-06}}{{cite web|url=http://www.stanfordcomputeroptics.com/applications/iccd-methods/ultra-high-speed-imaging.html|title=Ultra high speed CCD cameras capture the motion of light.|publisher=Stanford Computer Optics|access-date=2014-03-06}}

One picosecond is equal to 1000 femtoseconds, or 1/1000 nanoseconds. Because the next SI unit is 1000 times larger, measurements of 10⁻¹¹ and 10⁻¹⁰ second are typically expressed as tens or hundreds of picoseconds. Some notable measurements in this range include:

• 1.0 picoseconds (1.0 ps) – cycle time for electromagnetic frequency 1 terahertz (THz) (1 x 10¹² hertz), an inverse unit. This corresponds to a wavelength of 0.3 mm, as can be calculated by multiplying 1 ps by the speed of light (approximately 3 x 10⁸ m/s) to determine the distance traveled. 1 THz is in the far infrared.
• 1 picosecond – time taken by light in vacuum to travel approximately 0.30 mm
• 1 picosecond – half-life of a bottom quark
• ~1 picosecond – lifetime of a single {{chem|H|3|O|+}} (hydronium) ion in water at 20 °C{{cite web |url= http://bionumbers.hms.harvard.edu/bionumber.aspx?id=106550 |title= Lifetime of single hydronium (H3O+) ion at 20°C |publisher= BioNumbers |access-date=2011-10-10 }}
• picoseconds to nanoseconds – phenomena observable by dielectric spectroscopy
• 1.2 picoseconds – switching time of the world's fastest transistor (845 GHz, as of 2006){{cite web |author=Kloeppel |first=James E. |date=December 11, 2006 |title=World's Fastest Transistor Approaches Goal of Terahertz Device |url=http://news.illinois.edu/news/06/1211transistor.html |url-status=deviated |archive-url=https://web.archive.org/web/20110427064017/http://news.illinois.edu/news/06/1211transistor.html |archive-date=April 27, 2011 |website=University of Illinois News Bureau |publisher=University of Illinois Urbana-Champaign}}
• 1.7 picoseconds – rotational correlation time of water{{cite journal|last=Lankhorst|first=D.|author2=Schriever, J. |author3=Leyte, J. C. |title=Determination of the Rotational Correlation Time of Water by Proton NMR Relaxation in H217O and Some Related Results|journal=Berichte der Bunsengesellschaft für physikalische Chemie|year=1982|volume=86|issue=3|pages=215–221|doi=10.1002/bbpc.19820860308}}
• 3.3 picoseconds (approximately) – time taken for light to travel 1 millimeter
• 10 picoseconds after the Big Bang – electromagnetism separates from the other fundamental forces
• 34 picoseconds – signal rise time (20% to 80%) of a SFP+ transmitter for 10 Gigabit Ethernet.{{cite web|title=SFF-8431 Specifications for Enhanced Small Form Factor Pluggable Module SFP+|author=SFF Committee|url=https://www.10gtek.com/templates/wzten/pdf/SFF-8431-(SFP+%20MSA).pdf}}
• 10 to 150 picoseconds – rotational correlation times of a molecule (184 g/mol) from hot to frozen water{{Cite journal | last1 = Bulla | first1 = I. | last2 = Törmälä | first2 = P. | last3 = Lindberg | first3 = J. J. | last4 = Mikalsen | first4 = Ø. | last5 = Southern | first5 = J. T. | last6 = Edlund | first6 = K. | last7 = Eliasen | first7 = M. | last8 = Herskind | first8 = C. | last9 = Laursen | first9 = T. | last10 = Pedersen | first10 = P. M. L. | title = Spin Probe Studies on the Dynamic Structure of Dimethyl Sulfoxide-Water Mixtures | journal = Acta Chemica Scandinavica | volume = 29a | pages = 89–92 | year = 1975 | doi = 10.3891/acta.chem.scand.29a-0089| doi-access = free }}
• 100 picoseconds – Unit Interval of a 10 Gbit/s serial communication link, such as USB 3.1.{{cite web|title=Universal Serial Bus 3.1 Specification|url=https://manuais.iessanclemente.net/images/b/bc/USB_3_1_r1.0.pdf}}
• 108.7827757 picoseconds – transition time between the two hyperfine levels of the ground state of the caesium-133 atom at absolute zero
• 330 picoseconds (approximately) – the time it takes a common 3.0 GHz computer CPU to complete a processing cycle