Atomic clock with laser cooled single ions confined together in an electromagnetic ion trap
A
quantum clock
is a type of
atomic clock
with
laser cooled
single
ions
confined together in an
electromagnetic ion trap
. Developed in 2010 by physicists at the U.S.
National Institute of Standards and Technology
, the clock was 37 times more precise than the then-existing international standard.
[1]
The quantum logic clock is based on an aluminium spectroscopy ion with a logic atom.
Both the
aluminum
-based quantum clock and the
mercury
-based optical
atomic clock
track time by the ion vibration at an optical frequency using a
UV laser
, that is 100,000 times higher than the microwave frequencies used in
NIST-F1
and other similar time standards around the world. Quantum clocks like this are able to be
far more precise
than microwave standards.
Accuracy
[
edit
]
The NIST team are not able to measure clock ticks per second because the definition of a second is based on the standard NIST-F1, which cannot measure a machine more precise than itself. However, the aluminum ion clock's measured frequency to the current standard is
1
121
015
393
207
857
.4(7) Hz
.
[2]
NIST have attributed the clock's accuracy to the fact that it is insensitive to background magnetic and electric fields, and unaffected by temperature.
[3]
In March 2008, physicists at
NIST
described an experimental quantum logic clock based on individual
ions
of
beryllium
and
aluminum
. This clock was compared to NIST's
mercury
ion clock. These were the most accurate clocks that had been constructed, with neither clock gaining nor losing time at a rate that would exceed a second in over a billion years.
[4]
In February 2010, NIST physicists described a second, enhanced version of the quantum logic clock based on individual
ions
of
magnesium
and
aluminium
. Considered the world's most precise clock in 2010 with a fractional frequency inaccuracy of
8.6 × 10
?18
, it offers more than twice the precision of the original.
[5]
[6]
In terms of
standard deviation
, the quantum logic clock deviates one second every 3.68 billion (
3.68 × 10
9
) years, while the then current international standard NIST-F1
Caesium fountain
atomic clock uncertainty was about 3.1 × 10
?16
expected to neither gain nor lose a second in more than 100 million (
100 × 10
6
) years.
[7]
[8]
In July 2019, NIST scientists demonstrated such a clock with total uncertainty of
9.4 × 10
?19
(deviates one second every 33.7 billion years), which is the first demonstration of a clock with uncertainty below
10
?18
.
[9]
[10]
[11]
Quantum time dilation
[
edit
]
In a 2020 paper scientists illustrated that and how quantum clocks could experience a possibly experimentally testable
superposition
of proper times via time dilation of the theory of relativity by which time passes slower for one object in relation to another object when the former moves at a higher velocity. In "quantum time dilation" one of the two clocks moves in a superposition of two localized momentum
wave packets
,
[
further explanation needed
]
resulting in a change to the classical time dilation.
[13]
[14]
[12]
Other accurate experimental clocks
[
edit
]
The accuracy of quantum-logic clocks was briefly superseded by
optical lattice clocks
based on
strontium-87
and
ytterbium-171
until 2019.
[9]
[10]
[11]
An experimental optical lattice clock was described in a 2014 Nature paper.
[15]
In 2015
JILA
evaluated the absolute frequency uncertainty of their latest
strontium-87
429 THz (
429
228
004
229
873
.0 Hz
[16]
)
optical lattice clock at
2.1 × 10
?18
, which corresponds to a measurable
gravitational time dilation
for an elevation change of 2 cm (0.79 in) on planet Earth that according to JILA/NIST Fellow
Jun Ye
is "getting really close to being useful for
relativistic geodesy
".
[17]
[18]
[19]
At this frequency uncertainty, this JILA optical lattice optical clock is expected to neither gain nor lose a second in more than 15 billion (
1.5 × 10
10
) years.
[20]
See also
[
edit
]
References
[
edit
]
- ^
Ghose, Tia (5 February 2010).
"Ultra-Precise Quantum-Logic Clock Puts Old Atomic Clock to Shame"
.
Wired
. Retrieved
2010-02-07
.
- ^
Rosenband, T.; Hume, D. B.; Schmidt, P. O.; Chou, C. W.; Brusch, A.; Lorini, L.; Oskay, W. H.; Drullinger, R. E.; Fortier, T. M.; Stalnaker, J. E.; Diddams, S. A.; Swann, W. C.; Newbury, N. R.; Itano, W. M.; Wineland, D. J.; Bergquist, J. C. (28 March 2008).
"Frequency Ratio of Al+ and Hg+ Single-ion Optical Clocks; Metrology at the 17th Decimal Place"
(PDF)
.
Science
.
319
(5871): 1808?1812.
Bibcode
:
2008Sci...319.1808R
.
doi
:
10.1126/science.1154622
.
PMID
18323415
.
S2CID
206511320
. Retrieved
2013-07-31
.
- ^
"Quantum Clock Proves to be as Accurate as World's Most Accurate Clock"
. azonano.com. 7 March 2008
. Retrieved
2012-11-06
.
- ^
Swenson, Gayle (7 June 2010).
"Press release: NIST 'Quantum Logic Clock' Rivals Mercury Ion as World's Most Accurate Clock"
.
NIST
.
- ^
NIST's Second 'Quantum Logic Clock' Based on Aluminum Ion is Now World's Most Precise Clock
Archived
2010-09-05 at the
Wayback Machine
, NIST, 4 February 2010
- ^
C.W Chou; D. Hume; J.C.J. Koelemeij; D.J. Wineland & T. Rosenband (17 February 2010).
"Frequency Comparison of Two High-Accuracy Al+ Optical Clocks"
(PDF)
.
Physical Review Letters
.
104
(7): 070802.
arXiv
:
0911.4527
.
Bibcode
:
2010PhRvL.104g0802C
.
doi
:
10.1103/PhysRevLett.104.070802
.
PMID
20366869
.
S2CID
13936087
. Retrieved
9 February
2011
.
- ^
"NIST's Second 'Quantum Logic Clock' Based on Aluminum Ion is Now World's Most Precise Clock"
(Press release).
National Institute of Standards and Technology
. 4 February 2010. Archived from
the original
on 2010-09-05
. Retrieved
2012-11-04
.
- ^
"NIST-F1 Cesium Fountain Atomic Clock: The Primary Time and Frequency Standard for the United States"
.
NIST
. August 26, 2009
. Retrieved
2 May
2011
.
- ^
a
b
Brewer, S. M.; Chen, J.-S.; Hankin, A. M.; Clements, E. R.; Chou, C. W.; Wineland, D. J.; Hume, D. B.; Leibrandt, D. R. (2019-07-15).
"Al + 27 Quantum-Logic Clock with a Systematic Uncertainty below 10 ? 18"
.
Physical Review Letters
.
123
(3): 033201.
arXiv
:
1902.07694
.
doi
:
10.1103/PhysRevLett.123.033201
.
PMID
31386450
.
S2CID
119075546
.
- ^
a
b
Wills, Stewart (July 2019).
"Optical Clock Precision Breaks New Ground"
.
- ^
a
b
Dube, Pierre (2019-07-15).
"Viewpoint: Ion Clock Busts into New Precision Regime"
.
Physics
.
12
: 79.
doi
:
10.1103/Physics.12.79
.
S2CID
199119436
.
- ^
a
b
Smith, Alexander R. H.; Ahmadi, Mehdi (23 October 2020).
"Quantum clocks observe classical and quantum time dilation"
.
Nature Communications
.
11
(1): 5360.
arXiv
:
1904.12390
.
Bibcode
:
2020NatCo..11.5360S
.
doi
:
10.1038/s41467-020-18264-4
.
ISSN
2041-1723
.
PMC
7584645
.
PMID
33097702
.
Available under
CC BY 4.0
(some content of it has been used here).
- ^
"Timekeeping theory combines quantum clocks and Einstein's relativity"
.
phys.org
. Retrieved
10 November
2020
.
- ^
O'Callaghan, Jonathan.
"Quantum Time Twist Offers a Way to Create Schrodinger's Clock"
.
Scientific American
. Retrieved
10 November
2020
.
- ^
Bloom, B. J.; Nicholson, T. L.; Williams, J. R.; Campbell, S. L.; Bishof, M.; Zhang, X.; Zhang, W.; Bromley, S. L.; Ye, J. (22 January 2014). "An optical lattice clock with accuracy and stability at the 10?18 level".
Nature
.
506
(7486): 71?5.
arXiv
:
1309.1137
.
Bibcode
:
2014Natur.506...71B
.
doi
:
10.1038/s41586-021-04349-7
.
PMID
24463513
.
S2CID
4461081
.
- ^
Yasuda, Masami; Ido, Tetsuya.
"Report from TCTF/TCL JWG on Optical Frequency Metrology, TCTF Meeting, Delhi, India, 27 November 2017"
.
APMP
. Asia-Pacific Metrology Programme
. Retrieved
8 November
2021
.
- ^
T.L. Nicholson; S.L. Campbell; R.B. Hutson; G.E. Marti; B.J. Bloom; R.L. McNally; W. Zhang; M.D. Barrett; M.S. Safronova; G.F. Strouse; W.L. Tew; J. Ye (21 April 2015).
"Systematic evaluation of an atomic clock at 2 × 10
?18
total uncertainty"
.
Nature Communications
.
6
: 6896.
arXiv
:
1412.8261
.
Bibcode
:
2015NatCo...6.6896N
.
doi
:
10.1038/ncomms7896
.
PMC
4411304
.
PMID
25898253
.
- ^
JILA Scientific Communications (21 April 2015).
"About Time"
. Archived from
the original
on 19 September 2015
. Retrieved
27 June
2015
.
- ^
Laura Ost (21 April 2015).
"Getting Better All the Time: JILA Strontium Atomic Clock Sets New Record"
.
National Institute of Standards and Technology
. Retrieved
17 October
2015
.
- ^
James Vincent (22 April 2015).
"The most accurate clock ever built only loses one second every 15 billion years"
.
The Verge
. Retrieved
26 June
2015
.