The Hughston–Jozsa–Wootters theorem shows that any finite ensemble of quantum states can be prepared “at a distance,” and it has been used to demonstrate the insecurity of all bit commitment protocols based on finite quantum systems without superselection rules. In this paper, we prove a generalized HJW theorem for arbitrary ensembles of states on a C*-algebra. We then use this result to demonstrate the insecurity of bit commitment protocols based on infinite quantum systems, and quantum systems with Abelian superselection rules.

1.
Alfsen
,
E.
, Compact Convex Sets and Boundary Integrals (Springer, New York,
1971
).
2.
Bennett
,
C.
and
Brassard
,
G.
, “
Quantum cryptography: Public key distribution and coin tossing
,” in Proceedings of IEEE International Conference on Computers, Systems, and Signal Processing (IEEE, New York,
1984
), pp.
175
179
.
3.
Bennett
,
C.
,
Crépeau
,
C.
,
Jozsa
,
R.
, and
Langlois
,
D.
, “
A quantum bit commitment scheme provably unbreakable by both parties
,” Proceedings of the 34th Annual IEEE Symposium on the Foundations of Computer Science,
1993
, pp.
362
371
.
4.
Brassard
,
G.
,
Crépeau
,
C.
,
Mayers
,
D.
, and
Salvail
,
L.
, “
A brief review on the impossibility of quantum bit commitment
,” quant-ph/9712023.
5.
Bratteli
,
O.
, and
Robinson
,
D.
, Operator Algebras and Quantum Statistical Mechanics (Springer, New York,
1987
), Vol.
1
.
6.
Bub
,
J.
, “
The quantum bit commitment theorem
,”
Found. Phys.
31
,
735
756
(
2001
).
7.
Cassinelli
,
G.
,
De Vito
,
E.
, and
Levrero
,
A.
, “
On the decompositions of a quantum state
,”
J. Math. Anal. Appl.
210
,
472
483
(
1997
).
8.
Clifton
,
R.
,
Feldman
,
D.
,
Halvorson
,
H.
,
Redhead
,
M.
, and
Wilce
,
A.
, “
Superentangled states
,”
Phys. Rev. A
58
,
135
(
1998
).
9.
Davies
,
E.
, Quantum Theory of Open Systems (Academic, New York,
1976
).
10.
Hughston
,
L.
,
Jozsa
,
R.
, and
Wootters
,
W.
, “
A complete classification of quantum ensembles having a given density matrix
,”
Phys. Lett. A
183
,
14
18
(
1993
).
11.
Kadison
,
R.
and
Ringrose
,
J.
, Fundamentals of the Theory of Operator Algebras (American Mathematical Society, Providence, RI,
1997
).
12.
Kent
,
A.
, “
Unconditionally secure bit commitment
,”
Phys. Rev. Lett.
83
,
1447
(
1999
).
13.
Keyl
,
M.
,
Schlingemann
,
D.
, and
Werner
,
R.
, “
Infinitely entangled states
,”
Quantum Inf. Comput.
3
,
281
306
(
2003
).
14.
Kitaev
,
A.
,
Mayers
,
D.
, and
Preskill
,
J.
, “
Superselection rules and quantum protocols
,”
Phys. Rev. A
69
,
052326
(
2004
).
15.
Lo
,
H.-K.
, and
Chau
,
H. F.
, “
Is quantum bit commitment really possible?
Phys. Rev. Lett.
78
,
3410
(
1997
).
16.
Mayers
,
D.
, “
Unconditionally secure quantum bit commitment is impossible
,” in Proceedings of the Fourth Workshop on Physics and Computation, Boston,
1996
, pp.
224
228
.
17.
Mayers
,
D.
, “
Unconditionally secure quantum bit commitment is impossible
,”
Phys. Rev. Lett.
78
,
3414
(
1997
).
18.
Mayers
,
D.
, “
Superselection rules in quantum cryptography
,” quant-ph/0212159.
19.
Ozawa
,
M.
, “
Quantum measuring processes of continuous observables
,”
J. Math. Phys.
25
,
79
87
(
1984
).
20.
Pedersen
,
G.
, C*-algebras and Their Automorphism Groups (Academic, New York,
1979
).
21.
Popescu
,
S.
, “
Multi-party entanglement
,” MSRI lecture, December
2002
.
22.
Schwartz
,
J.
, “
Two finite, non-hyperfinite, non-isomorphic factors
,”
Commun. Pure Appl. Math.
16
,
19
26
(
1963
).
23.
Srinivas
,
M.
, “
Collapse postulate for observables with continuous spectra
,”
Commun. Math. Phys.
71
,
131
158
(
1980
).
24.
Takesaki
,
M.
, Theory of Operator Algebras I (Springer, New York,
1979
).
25.
Tomita
,
M.
, “
Harmonic analysis on locally compact groups
,”
Math. J. Okayama Univ.
5
,
133
193
(
1956
).
This content is only available via PDF.
You do not currently have access to this content.