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ASC’12 Portland, OR 1
JOSEPHSON DIGITAL ELECTRONICSIN THE SOVIET UNION
Konstantin K. Likharev
Acknowledgments of kind help from:
S. Berkovich, A. Kirichenko, G. Lapir, O. Mukhanov, V. Semenov
2
1
11
ϕψψ ie= 2
22
ϕψψ
ie=
Experimental observation:
P. Anderson and J. Rowell, 1963
S. Shapiro, 1963
This image cannot currently be
displayed.
I
0
CI+
CI−
22
πϕ
π+≤≤−
h/2
const)(
Ve
tt
J
J
≡
+=
ω
ωϕ
( )constsin += tII JC ω
Flux Quantization and Josephson Effect
21,sin ϕϕϕϕ −≡= cII
eVdt
dH
ti k
k 2ˆ =⇒=∂
∂ ϕψ
ψhh
B. Josephson, 1962F. London, 1950
−∇≡ A
q
mqj
r
h
rhrϕψ
2
, 2
∫∫ =Φ=⋅A
n
C
rdBldArr
nldAq
πϕ 2=∆=⋅∫rr
h
qn
hπ2, 00 ≡ΦΦ=Φ
B. Deaver, Jr. and W. Fairbank (1961)R. Doll and M. Näbauer (1961)
ASC’12 Portland, OR
3
0
22
yield
and2
Φ
Φ−=
Φ−=
−=Φ
=
πϕ
ϕ
e
Vdt
d
eVdt
d
h
h
Josephson effect plus flux quantization:
∫=ΦA
n rdB2
0
2sinΦ
Φ−Φ=Φ πCe LI
1− 0 1 2 31−
0
1
2
1033.02
0
=Φ
≡ cL
LIπβ
0Φ
Φ
0/ ΦΦe
rf SQUID dc SQUID
Memory! Logic!
IV
gI
SQUIDs
cI
gI0
ASC’12 Portland, OR
Parameter scales:
Bulk version:
a ~ 3 mm
τ ~ 50 µs
Thin-film version:
w ~ 1 mm, Ic ~ 1 A
L ~ 10-11 H, R ~ 10-3 Ω
τ ~ L/R ~ 10 ns
E ~ LIc2 ~10-11 J/bit
If scaled down to w ~100 nm:
Ic ~ 100 µA, R ~ 10 Ω
τ ~ 1 ps, E ~ 10-19 J/bit
(right in the present-day’s
ballpark!)
4
Cryotron Age
D. A. Back (MIT LL), 1954
J. W. Brewer (IBM), 1957
All figures from: J. W. Brewer, Superconductive Devices, McGraw-Hill, 1962J. W. Crowe (IBM), 1957
ASC’12 Portland, OR
In the Soviet Union before 1967…
SimonBerkovich
Kapitsa’s IPP, Moscow, 1960
In 1960, S.B. joined ITMiVT’s
group headed by A. Chentsov,
and in 1966 formed a large
group in NIIFP (Zelenograd)
Academgorodok, Novosibirsk, 1966
GennadyLapir
SimonBerkovich
ASC’12 Portland, OR
6
Latching logic (inductively coupled version):
BI
V
HILR
LRZ =
BILR
)0(CI
)( HC II
I
VeT /)(2∆0
Latching Logic (I)
Major players: IBM Yorktown Heights, Bell Labs; UC Berkeley (T. Van Duzer)
BI
V
HI 0Φn
SFQ memory cell:
3~LβBI
HI0
1=n0=n
→→→→ WRITE 0
→→→→ WRITE 1
→ READ 1
retention
S → R switching at I > Ic
1 ns1 mV
J. Matisoo (IBM), 1966
J. Matisoo, 1967
traditional cryotron
“tunneling
cryotron”
ASC’12 Portland, OR
7
Major problems:
- JJ technology (Pb alloys)
- needs ac power/clock (crosstalk, etc.)
- punchthrough effect at reset (1 ns scale)
Fujitsu’s 8-bit DSP:
- 6,300 gates (23,000 JJs)
- 12 mW, fc < 1 GHz
Latching Logic (II)
CI
RI
I
VeT /)(2∆0
S. Hasuo, 1993
“Nb-trilayer” (Nb/Al/AlOx/Nb) junctions:
M. Gurvitch et al.
(Bell Labs), 1983 S. Hasuo, 1993
ASC’12 Portland, OR
8
Non-Latching JJ Electronics
Non-latching JJ cryotrons: Problems:
- best fit for self-shunted JJs
- poor fab!
RE: nice recent work
- CEA-Grenoble (TaxN)
- NIST-Boulder (NbxSi)
Zhukin, Ukraine, 1977
BI
I
V0
LR
outV
IgorVoitovych
Guess who?
VladimirMakhov
VasiliSemenov
Moscow, 1977
US Patent 4,146,030 (filed Aug. 1977)
PeterBakhtin
ASC’12 Portland, OR
9
Background ideas:
E. Goto, 1954; C. Bennett, 1973
Parametric Quantron: Moscow 1976
(later re-invented as QFP):
Reversible
operation:
Irreversible
operation:Discarding
“fundamental limits”
on power
consumption:
(i) thermodynamic:
E > kBT ln2
(ii) quantum:
E > h/τ
BOTH WRONG!
)(
1ln
ωτ
τω
ω
τω
p
Tk
E
c
c
B
×
>h
Actual bounds:
KKL, 1982KKL, 1977
Reversible Computation (I)
ASC’12 Portland, OR
10
Circuits:
Constructive example:
fast convolver:
y(n) = Σkx(n)×h(n-k)
- irreversible:
- reversible:
For 8 bits, 1024 points:
30 nW @ 1 GHz & 4.2 K; but: 9.2×106 PQs
S. Rylov et al., 1987
KL, 1982
Toward experimental demo:
J. Ren and V. Semenov, 2011
Reversible Computation (II)
ASC’12 Portland, OR
Sacrificing reversibility at a few critical points,
hardware demands may be dramatically quenched
Two other problems are much worse:
(i) relatively low speed, and
(ii) very low parameter margins
Reversible Computation (III)
tunnel
junctions
Clock
field
Signal field (say,
from a similar cell
nearby)
-e
KKL and A. Korotkov, 1996
Single-electron parametron:
“Clocked QCA [Quantum-Dot Cellular
Automata]”
Stony Brook, 1996 Notre Dame, 1997
A. Orlov et al., 2001
12
SQUID as an SFQ pulse
generator:
V(t)
SFQ Pulse
I(t)It
Faraday's Law:
V(t) = dΦ/dt
for the SFQ pulse:
∫V(t)dt = Φ0 ≈ 2 mV-ps
Φ0
J. Buizacchelli et al. (IBM), 1995
t, d d’ ~ 100 nm
wt
d'
d
Superconducting
striplines:
I(t)
J. Hurell and A. Silver, 1978
Nb/Si0 Nb/Si02
V. Semenov and KKL, 1991
SFQ Pulses
ASC’12 Portland, OR
13
C. Hamilton and F. Lloyd, 1982
Experimental demonstration (up to 100 GHz):
K. Nakajima et al., 1976
SFQ vortex logic (Tohoku U.):
J. Hurell and A. Silver, 1978
J. Hurrell et al., 1980
SQUID switching by SFQ pulses:
SFQ Vortices and Pulses
ASC’12 Portland, OR
14
Crucial new circuit:
latching inverter
Φ0
Φ0
O. Mukhanov and V. Semenov, 1985
Iin(t)
Vout
RSFQ Circuits: The Idea
Story of “R” in RSFQ:
from Resistive to RapidFrom http://pavel.physics.sunysb.edu/RSFQ/Lib/
ASC’12 Portland, OR
15
RSFQ Circuits: First Demo
Fist experimental RSFQ circuit (IRE + MSU):
V. Koshelets et al., 1987
Moscow, 1989
ASC’12 Portland, OR
Worked from 0 to 30 GHz
(for 10-um “technology”)
16
S. Shokhor et al., 1995
YBCO RSFQ circuit working up to 30 K
However, a fundamental problem:
IC ∝∝∝∝ T (fluctuations)
L ~ Φ0/IC (quantization)
Lmin ∝∝∝∝ λλλλ(T) (striplines)
fine if λλλλ(0) ∝∝∝∝ 1/TC , but this is not so
By now: TFF up to 500 GHz
(T. Kimura et al., 2009)
Chernogolovka, 1987
KKL, V. Semenov and A. Zorin, "New Possibilities for Superconductor
Electronics“, in: Superconducting Devices, ed. by S. T. Ruggiero and D.
A. Rudman, Academic Press, Boston, pp. 1-49 (1990).
High-Tc RSFQ?
ASC’12 Portland, OR
17
The Politburo Ordeal, and the End
March 1987: Soviet Physics Woodstock
March-April 1998: The Politburo Ordeal
Late 1998 – June 2000: Project “Contact”
Summer 2000: US trip (incl. ASC talk)
Early 2001: the departure
August 1991: Communism falls
December 1991: the USSR falls apart Stony Brook, 1991
Moscow, 1988
ASC’12 Portland, OR
18
Thank You!
Questions/remarks:
klikharev@notes.cc.sunysb.edu
ASC’12 Portland, OR
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