For the present effective ultrafast quantum switching, overlap between the pump
and dump pulses is essential: the resultant electric field is rotated as an elliptically
polarized one in the overlapped region, and the electric field forces the rotating π
electrons to induce the reverse rotation that occurs in this overlapped region. As a
result, the electronic angular momentum or coherence between two electronic
quasi-degenerate states is erased.
3.7 Coherent π-Electron Rotations in Aromatic Chain
Molecules
For a more general application of our method, we are interested in a covalently
linked large molecular chain consisting of n-aromatic rings. Here we briefly
introduce our approach to a covalently linked aromatic ring molecule with point
group C 2 . Here for simplicity, phenol and benzene are taken as aromatic ring
molecules. We also note that this approach is not necessarily restricted to a planar
chiral aromatic molecule, but can be directly applied to nonplanar one. In Fig. 6 we
0.1
/
Z
l
/
X
l
(a)
(b)
F/GVm -1
t/fs
0
100
200
300
0.0
-0.5
-1.0
0.5
1.0
( )
1
ab
e
( )
1
ab
e
( )
1 2
b b
e
( )
1 2
b b
e
( )
1 2
b b
e
( )
1 2
b b
e
( )
1
ab
e
( )
1
ab
e
0.1
0.0
-0.1
-0.1
0
100
200
300
0.0
+
_
+
_
+
_
+
_
Fig. 5 a Sequential four-step
switching of π-electron
rotations in (P)-2,2′-biphenol.
b Electric fields of the
sequence of overlapped pump
and dump pulses
172
H. Mineo and Y. Fujimura
and dump pulses is essential: the resultant electric field is rotated as an elliptically
polarized one in the overlapped region, and the electric field forces the rotating π
electrons to induce the reverse rotation that occurs in this overlapped region. As a
result, the electronic angular momentum or coherence between two electronic
quasi-degenerate states is erased.
3.7 Coherent π-Electron Rotations in Aromatic Chain
Molecules
For a more general application of our method, we are interested in a covalently
linked large molecular chain consisting of n-aromatic rings. Here we briefly
introduce our approach to a covalently linked aromatic ring molecule with point
group C 2 . Here for simplicity, phenol and benzene are taken as aromatic ring
molecules. We also note that this approach is not necessarily restricted to a planar
chiral aromatic molecule, but can be directly applied to nonplanar one. In Fig. 6 we
0.1
/
Z
l
/
X
l
(a)
(b)
F/GVm -1
t/fs
0
100
200
300
0.0
-0.5
-1.0
0.5
1.0
( )
1
ab
e
( )
1
ab
e
( )
1 2
b b
e
( )
1 2
b b
e
( )
1 2
b b
e
( )
1 2
b b
e
( )
1
ab
e
( )
1
ab
e
0.1
0.0
-0.1
-0.1
0
100
200
300
0.0
+
_
+
_
+
_
+
_
Fig. 5 a Sequential four-step
switching of π-electron
rotations in (P)-2,2′-biphenol.
b Electric fields of the
sequence of overlapped pump
and dump pulses
172
H. Mineo and Y. Fujimura