PHYSICAL REVIEW APPLIED
20,
044018 (2023)
Editors’ Suggestion
Near-infrared hybrid quantum photonic interface for
171
Yb
3
+
solid-state
qubits
Chun-Ju Wu,
1,2,3,4,
†
Daniel Riedel,
1,
†,‡
Andrei Ruskuc,
1,2,3
Ding Zhong,
1,2,3
Hyounghan Kwon,
1,3,
§
and
Andrei Faraon
1,2,3,
*
1
Thomas J. Watson, Sr., Laboratory of Applied Physics, California Institute of Technology, Pasadena, California,
USA
2
Institute for Quantum Information and Matter, California Institute of Technology, Pasadena, California, USA
3
Kavli Nanoscience Institute, California Institute of Technology, Pasadena, California, USA
4
Division of Physics, Mathematics and Astronomy, California Institute of Technology, Pasadena, California, USA
(Received 12 December 2022; revised 18 July 2023; accepted 1 September 2023; published 6 October 2023)
171
Yb
3
+
in YVO
4
is a promising candidate for building quantum networks with good optical address-
ability, excellent spin properties and a secondary nuclear-spin quantum register. However, the associated
long optical lifetime necessitates coupling to optical resonators for faster emission of single photons and
to facilitate control of single
171
Yb ions. Previously, single
171
Yb ions were addressed by coupling them to
monolithic photonic crystal cavities fabricated via lengthy focused ion beam milling. Here, we design and
fabricate a hybrid platform based on ions coupled to the evanescently decaying field of a GaAs photonic
crystal cavity. For the most strongly coupled ion close to the GaAs-YVO interface, we find a 64-fold reduc-
tion in lifetime corresponding to a Purcell enhancement of 179. For an ion with a Purcell enhancement
of 21, we experimentally detect and demonstrate coherent optical control. The results show a promising
route toward a quantum network with
171
Yb-YVO
4
using a highly scalable platform that can readily be
applied to other quantum emitters in the near-infrared.
DOI:
10.1103/PhysRevApplied.20.044018
I. INTRODUCTION
Transmitting quantum information and distributing
entanglement through quantum networks are essential
components in quantum technology and have applica-
tions in quantum communication and distributed quan-
tum computing [
1
,
2
]. Building a scalable optical quantum
network requires nodes with lifetime-limited optical tran-
sitions, efficient optical interfaces, long spin coherence
times, high-fidelity spin and optical control, and multi-
qubit accessibility at each node. Among different plat-
forms, optically addressable solid-state spin qubits are
promising candidates due to the possibility of integration
with nanofabricated devices leading to scalability [
3
,
4
].
Possible candidates include nitrogen vacancies [
5
,
6
], sil-
icon vacancies [
7
,
8
], and tin vacancies [
9
,
10
] in diamond,
color centers in SiC [
11
,
12
], defects in silicon [
13
], and
rare-earth ions in crystals [
14
,
15
]. Rare-earth ions have
*
Faraon@caltech.edu
†
These authors contributed equally to this work.
‡
Present address: AWS Center for Quantum Networking,
Boston, Massachusetts, USA.
§
Present address: Center for Quantum Information, Korea
Institute of Science and Technology, Seoul, Republic of Korea.
been shown to possess long spin and optical coherence
times in various hosts and will be the focus of this work
[
16
,
17
].
Previously, we demonstrated that
171
Yb
3
+
ions inside
YVO
4
have spin coherence times exceeding 10 ms,
over 99.9% single-qubit gate fidelities, 95% post-selected
optical readout and initialization fidelity, and additional
nuclear spin qubit control, which are essential proper-
ties for building a quantum network [
14
,
18
]. In rare-
earth ion platforms, coherent 4
f
-4
f
optical transitions are
only weakly allowed inside crystals, therefore it is essen-
tial to couple ions to cavities with large quality factors
and small mode volumes to increase the emission rate
through Purcell enhancement. However, the nanofabrica-
tion of monolithic nanophotonic cavities from common
rare-earth host materials is limited due to the unavail-
ability of high-quality thin films and selective etching
chemistries (aside from a few examples [
19
–
21
]). Here we
demonstrate a near-infrared hybrid platform comprising a
separately fabricated photonic crystal cavity that is subse-
quently transferred onto the host crystal [Fig.
1(a)
][
22
,
23
].
This platform possesses a smaller mode volume compared
to Fabry-Perot microcavities [
24
,
25
], and, unlike the pre-
vious approach of focused ion beam milling [
14
,
26
], does
not lead to crystal damage.
2331-7019/23/20(4)/044018(7)
044018-1
© 2023 American Physical Society
CHUN-JU WU
et al.
PHYS. REV. APPLIED
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Achieving significant enhancement in a hybrid photonic
platform requires using a material with several impor-
tant features. It needs to be transparent at the target
wavelength, the refractive index needs to be significantly
higher than the target crystal, and high-quality thin-film
material should be readily available. The optical transition
of
171
Yb
3
+
-YVO
4
at 984.5 nm precludes the use of sili-
con. Hence, we choose GaAs as the photonic layer due to
its transparency in the near- infrared, its large refractive
index (
n
YVO,
c
=
2.17,
n
GaAs
=
3.52) and the availability of
wafer-scale thin films. High-quality-factor photonic crys-
tal cavities have been fabricated at this wavelength using
electron beam lithography, thus enabling mass production
[
27
,
28
]. Recently, it has been demonstrated that the GaAs
platform is amenable to scaling up deterministic solid-state
photon-emitter interfaces [
29
]. In addition, wafer bonding
techniques enable the creation of large-scale photonic inte-
grated circuits [
30
]. In the following sections, we present
the design and fabrication of these hybrid devices, and
experimentally demonstrate optical control of single
171
Yb
ions.
II. DEVICE DESIGN AND FABRICATION
Yb ions inside an a-cut YVO
4
crystal are coupled to a
one-dimensional photonic crystal cavity with fundamental
TE mode [
31
], where the electric field is mostly aligned
with the
c
axis of the crystal. The photonic crystal design
is based on unit cells with elliptical holes to engineer a
band gap at 984.5 nm. A localized cavity mode is formed
by quadratically tapering 20 central periods of a 44-period
photonic crystal [Figs.
1(b)
and
1(c)
]. This is optimized to
reduce radiation loss while maintaining a small mode vol-
ume. We engineer preferential cavity-waveguide coupling
on one side by removing 11 mirror periods. The design
of GaAs photonic crystal is chosen to enable high field
penetration into YVO
4
without significantly decreasing the
quality factor. We chose an effective index corresponding
to the geometric mean of YVO and GaAs. Depending on
the loss mechanisms a systematic study might yield bet-
ter performance. Figures
1(b)
and
1(c)
show the simulated
y
-directed electric field (
E
y
) that will be aligned with the
Yb optical dipole moment along the
c
axis, along with the
pertinent cavity dimensions. The simulated squared elec-
tric field magnitude (
|
E
|
2
) at the YVO
4
-GaAs interface
is 40% of the maximum
|
E
|
2
inside the GaAs layer. The
effective mode volume is about 1.7
(λ/
n
YVO
4
)
3
(normalized
according to the strongest electric field in YVO
4
right at
the surface) and the simulated radiatively limited quality
factor is over 1
×
10
6
.
∣
∣
E
y
∣
∣
2
evanescently decays with dis-
tance from the interface, and the 1
/
e
depth is 42 nm. To
couple light from the cavity into a fiber, we utilize a fully
etched grating coupler [
32
]. The grating coupler efficiency
is optimized by modifying the grating dimensions leading
to a simulated efficiency of about 25%.
Devices are fabricated on an epitaxial GaAs wafer using
a standard electron-beam lithography procedure with an
acceleration voltage of 100 kV (Raith EPBG 5000) [
27
].
A 500 nm positive-tone resist (ZEP) is patterned and sub-
sequently developed using
n
-amyl acetate (ZED, Zeon
(a)(b)(c)
(d)(e)(f)
FIG. 1. Hybrid device platform for coupling to
171
Yb-YVO
4
. (a) The device schematic. The GaAs photonic crystal cavity and YVO
4
crystal are shown in gray and yellow, respectively. Yb ions are shown with orange arrows and are located inside YVO
4
. The crystal
axes are shown next to the coordinate axes. The grating coupler (blue rectangle) is used for coupling light to a free-space setup. The
photonic crystal cavity is indicated with a white rectangle. (b),(c) Simulated
E
y
field of the fundamental TE mode in the
X
-
Y
and
Y
-
Z
planes, respectively. Note the evanescent decay of electric field inside YVO
4
. (d) Scanning electron microscope image of the
suspended GaAs photonic crystal cavity before transferring onto YVO
4
. (e) Optical image of the transferred device. The darker yellow
substrate under the GaAs photonic crystal cavities is YVO
4
. (f) Cavity reflection spectrum after transferring onto YVO
4
.Dataare
shown in green dots and overlaid with a fitted black line, which gives a quality factor of 5300.
044018-2
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PHYS. REV. APPLIED
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Corp.). The resist serves as the etch mask for an opti-
mized inductively coupled plasma reactive-ion etcher with
Cl
2
-Ar chemistry. Devices are undercut by etching an
Al
0.8
Ga
0.2
As sacrificial layer in HF and cleaned subse-
quently using H
2
O
2
and KOH to remove any residues [Fig.
1(d)
]. Finally, suspended GaAs photonic crystal cavities
are transferred onto the YVO
4
surface using a stamping
technique [
22
]. Devices are aligned with the
a
axis and are
perpendicular to the
c
axis. We use a polydimethylsiloxane
stamp covered by a thin film of polycarbonate to pick up
devices and subsequently release them onto YVO
4
using
a transfer stage. The success rate of this procedure is over
90%. The YVO
4
crystal used in this experiment was pol-
ished from an undoped boule (Gamdan Optics) with an Yb
concentration of 0.14 parts per million. The optical image
after the transfer is shown in Fig.
1(e)
. The device used in
these measurements has a quality factor of 5300 after trans-
ferring onto YVO
4
[Fig.
1(f)
]. Typical quality factors of
the devices before and after transfer are 15 000 and 5000,
respectively, and are likely limited by the imperfect device
fabrication and surface absorption [
28
].
III. DETECTION OF SINGLE YTTERBIUM IONS
IN YVO
4
Experiments are performed in a Bluefors
3
He fridge
(LD-He250) at 0.5 K and zero magnetic field. The exper-
imental setup is depicted in Fig.
2(a)
, where acousto-optic
modulated laser pulses are sent through a 99 : 1 beam
splitter and focused onto the grating coupler through an
aspheric lens doublet. The ion emission is sent back
through the same fiber, and 99% of the light is directed
to a superconducting nanowire single-photon detector. The
light coupling is optimized using an
x
-
y
-
z
nanopositioner
(Attocube), and the device resonance is tuned to the ion
emission frequency through nitrogen condensation.
Figure
2(b)
shows a resonant pulsed photoluminescence
spectrum, where ion emission has been distinguished from
the excitation in the time domain. The zero frequency offset
corresponds to emission from Yb isotopes with no nuclear
spin. At zero magnetic field, these isotopes contain degen-
erate Kramers doublets in both the ground and excited
states [
33
]. The arrows indicate the ions used in this work.
To demonstrate single-ion addressability, a single-
detector pulsed
g
2
(
t
)
measurement was performed on the
ion indicated by the blue arrow [Fig.
2(c)
]. The result-
ing
g
2
(0) is 0.26
±
0.09, lower than the two-ion limit of
0.5. The
g
2
(
t
)
measurement demonstrates a weak bunching
feature, likely caused by spectral diffusion of the optical
transition. By modeling spectral diffusion via rate equa-
tions, we derived and fitted the following function to the
g
2
(
t
)
data [34]:
g
(
2
)
(
t
)
=
[1
+
(τ
w
/τ
−
1
)
exp
(
−|
t
|
/τ )
]
×
[1
−
exp
(
−
(
r
+
1
/τ
ion
)
|
t
|
)
],
(1)
(a)
(b)
(c)(d)
FIG. 2. Experimental setup and detection of single Yb ions. (a)
Experimental setup. Optical pulses from two frequency locked
lasers, labeled A and C according to the driven optical transition
[Fig.
3(a)
], are sent to the device located in a
3
He fridge at 0.5
K. Emitted photons are routed to a superconducting nanowire
single-photon detector (SNSPD) in the same cryostat. Laser
pulses are shaped using two double-pass acousto-optic modula-
tors, and optical pulses are removed from the detection through
time filtering and an acousto-optic modulator shutter setup. (b)
Resonant photoluminescence spectrum. The large emission peak
at 3 04 505 GHz corresponds to Yb isotopes with no nuclear spin.
Isolated peaks inside the spectrum are mostly single Yb ions,
the arrows indicate ions measured in subsequent experiments.
Data was taken with 10 s integration time and 50 kHz repeti-
tion rate for each point. The fitted linewidth of red and blue ions
are 27.3 MHz and 15.9 MHz, respectively.(c) Pulsed
g
(
2
)
(
t
)
mea-
surement of the ion indicated with a blue arrow shows
g
(
2
)
(
0
)
=
0.26
±
0.09. (d) Lifetime measured through time-resolved pho-
toluminescence of ions indicated by red (4.2
±
0.1
μ
s) and
orange (32
±
2
μ
s) arrows are shown with corresponding colors.
Experimental data are shown with dots and overlaid with fit-
ted exponential decays. The fit to the orange curve also includes
an additional contribution from background bulk ions due to its
lower intensity. Bulk lifetime is shown with a black line.
where
τ
is the spectral diffusion rate,
τ
w
is the rate of ion
diffusion out of the detection window,
r
is the pumping
rate, and
τ
ion
is the lifetime of the emitter [
34
]. We can
derive a spectral diffusion correlation timescale of about
1 ms. The ion indicated by the red arrow has the short-
est lifetime in this sample, measured to be 4.2
±
0.1
μ
s
[Fig.
2(d)
]. This corresponds to a lifetime reduction of
64 times, which is consistent with the maximum lifetime
044018-3
CHUN-JU WU
et al.
PHYS. REV. APPLIED
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(a)
(b)
(d)(e)
(c)
FIG. 3. Coherent optical control of a single
171
Yb ion. (a) Energy level structure of
171
Yb inside YVO
4
at zero magnetic field.
Transition A (cavity enhanced) is shown in blue; transition C (non-enhanced) is shown in red. Cavity enhanced decay is shown with a
dashed arrow.
|
0
g
,
|
1
g
,
|
0
e
,
|
1
e
are magnetic field insensitive forming clock transitions. (b) Pump-probe measurement of the
171
Yb
optical transitions. The pump frequency is varied around the C-transition with probe frequency fixed to the A-transition. In subsequent
measurements, the ion is partially initialized by repeatedly pumping on this transition. The difference between the frequency noted
in Fig.
3(a)
and the measurement could be due to strain at the site of the ion. (c) Optical Rabi oscillation on the A-transition. (d)
Optical Ramsey measurement on the A-transition gives
T
∗
2
=
69
±
15 ns. (e) Optical echo measurement on the A-transition gives
T
2
=
330
±
50 ns.
reduction (
β
F
p
=
83) predicted by the Purcell effect [
35
].
β
=
0.35 is the branching ratio of the transition [
14
]and
F
p
,max
=
(
3
/
4
π
2
)(λ/
n
)
3
(
Q
/
V
)
=
237. From the predicted
maximum Purcell factor, measured lifetime, and the decay
profile of the electric field strength given in Sec.
II
, we can
derive maximum depths of the ions shown in Fig.
2(d)
,
which are 12 nm and 101 nm for the red and orange ion,
respectively.
IV. COHERENT OPTICAL CONTROL OF A
SINGLE YTTERBIUM-171 ION
While Yb isotopes without nuclear spin show bright
emission without initialization, they suffer from poor
coherence times due to first-order susceptibility of transi-
tion frequencies to magnetic fields. Hereafter, we focus on
171
Yb ions which have an additional 1/2 nuclear spin giv-
ing a zero-field hyperfine energy-level structure shown in
Fig.
3(a)
. These ions exhibit optical and spin clock tran-
sitions between the
|
0
g
,
|
1
g
,
|
0
e
,and
|
1
e
levels, which
are first-order insensitive to magnetic field noise, yielding
enhanced coherence properties [
14
]. The A-transition has
its dipole moment along the
c
axis of the crystal; it is copo-
larized with, and enhanced by, the cavity. Furthermore, it
has no overlap with other Yb isotopes, making it suitable
for optical readout. The C-transition has dipole moment
perpendicular to the
c
axis of the crystal and is used for
optical pumping and initialization.
To verify that the ion indicated by the orange arrow is
171
Yb [Fig.
2(b)
], we performed a pump-probe measure-
ment, where we varied the pump laser frequency and mea-
sured the photoluminescence on the A-transition. When
the pump laser is resonant with the C-transition, the ion
will be partially initialized into
|
1
g
and have brighter
emission [Fig.
3(b)
]. This initialization is performed prior
to all subsequent measurements.
Resonant photoluminescence with varied excitation
pulse length on the A-transition shows optical Rabi oscil-
lation [Fig.
3(c)
]. In this measurement, initialization is
periodically applied after each sequence of 50 readout
pulses. Combined with the limited cyclicity of the readout
transition, this acts to saturate the photon counts and cre-
ate a flat top feature. This ion has a lifetime of 32
±
2
μ
s,
leading to an A-transition cyclicity of 13 [
14
]. Characteri-
zation of the optical coherence properties is first performed
with an optical Ramsey measurement, which includes two
optical
π/
2 pulses with varied separation. We measured
T
∗
2
=
69
±
15 ns corresponding to an effective linewidth
of 4.6 MHz. The short-timescale optical frequency stabil-
ity is measured using an echo consisting of an additional
intermediate optical
π
pulse to rephase the coherence,
yielding
T
2
=
330
±
50 ns.
044018-4
NEAR-INFRARED HYBRID QUANTUM PHOTONIC INTERFACE. . .
PHYS. REV. APPLIED
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In these experiments, we were unable to perform opti-
cal coherence measurements for some of the ions that have
shorter lifetimes. Ions in these hybrid devices with larger
Purcell factors are closer to the surface and therefore more
susceptible to surface defects. We postulate that the result-
ing charge noise could lead to excess spectral diffusion and
deteriorated coherence properties. By contrast, in previ-
ously studied monolithic devices [
14
], well-coupled ions
showed 1
μ
s postselected optical Ramsey and lifetime-
limited optical echo (4
μ
s) coherence times since they were
centrally located and farther from surfaces. The next step
would be to characterize ion statistics with different Purcell
factors and understand the limiting factor for the optical
coherence in these hybrid devices.
V. CONCLUSION AND OUTLOOK
In this work, we fabricate suspended GaAs photonic
crystal cavities and transfer them onto YVO
4
with a suc-
cess rate of about 90%. We use a cavity with a quality
factor of 5300 to address single
171
Yb ions, show a lifetime
reduction of 64 times, and measure their optical coherence
properties.
In the future, developing coherent microwave control
of the spin transition will be essential. To improve the
platform and increase count rates, refining fabrication of
the photonic crystal cavity through surface passivation
and further optimization of the lithographic procedure
are crucial [
28
,
36
]. Switching to a shallow-etched grat-
ing coupler can also increase the waveguide to free-space
coupling efficiency [
37
], and the overall photon collection
rate into the waveguide can be improved by optimizing
the cavity-waveguide coupling [
38
]. If the optical coher-
ence is limited by surface proximity, we could dope Yb
ions at different depths and characterize their properties.
Optimizing the choice of the host crystal can also signifi-
cantly improve the optical coherence [
16
,
39
]. Additional
improvements could be attained by removing polishing-
induced strain through plasma etching [
40
] and controlling
the surface chemistry through systematic study of surface
cleaning and preparation techniques [
41
]. Given the fab-
rication capability and the flexibility of the hybrid GaAs
platform, combined with the excellent properties of
171
Yb-
YVO
4
, we think this approach is a promising route to build
a quantum network.
ACKNOWLEDGMENTS
This work was funded by Office of Naval Research
award no. N00014-19-1-2182, National Science Foun-
dation Award No. 1936350, DOE-QIS program (DE-
SC0019166), and Northrop Grumman. C.-J.W. acknowl-
edges the support from a Taiwanese government scholar-
ship. D.R. acknowledges support from the Swiss National
Science Foundation (Project No. P2BSP2_181748). A.R.
acknowledges the support from Eddleman Graduate Fel-
lowship. D.R. contributed to this work prior to joining
AWS. The device nanofabrication was performed in the
Kavli Nanoscience Institute at the California Institute
of Technology. We thank Joonhee Choi, Jake Rochman,
Ioana Craiciu, Tian Xie, Mi Lei, Rikuto Fukumori, and
Helena Guan for discussion, and Matt Shaw for help with
superconducting photon detectors.
APPENDIX: DEVICE SIMULATION
Here we present more information about the device sim-
ulation. In the device, there are three different channels,
κ
scatter
,
κ
WG, trans
,and
κ
WG, refl
, that couple light out of the
cavity, where
κ
scatter
is the scattering rate, and
κ
WG, trans
and
κ
WG, refl
are the rates of light coupling to the waveguide
in the transmitted and reflected direction with respect to
the incoming light. Our measurement configuration relies
on photons that are coupling back to the reflected direc-
tion, therefore it is important that
κ
WG, refl
is the dominant
channel. In Fig.
4(a)
, we show how the designed quality
factor is affected by the additional mirror number on both
sides of the cavity. This shows that
κ
scatter
=
1
/
Q
max
only
dominates at large mirror numbers in the simulation. In the
experiment, we choose one side to have 12 mirror periods
outside the tapered region, while the other side only has
one, so that
κ
WG, refl
is the dominant channel.
The driving of transitions with dipole moment along
the crystal
a
axis is essential for initialization. One con-
tribution to this drive comes from the input field that is
perpendicular to the cavity mode (there is no TM band gap
in our design). The other comes from a misalignment of
the cavity mode field with respect to the crystal
c
axis.
Figure
4(b)
shows a histogram of the ratio of
x
-and
y
-
directed electric field strengths of our mode [Fig.
1(a)
]. The
z
direction is not shown because the electric field strength
is negligible. For positions that have
|
E
y
|
>
0.5
|
E
y
,max
|
, the
median
|
E
x
|
/
|
E
y
|=
0.02. These show that both the TM
waveguide mode and the TE cavity mode can contribute
to C-transition driving.
(a)(b)
FIG. 4. Simulated device properties. (a) The simulated quality
factor with different mirror numbers on both sides of the cavity.
(b) Histogram of the
x
-and
y
-directed electric field strength ratio
at positions with
|
E
y
|
>
0.5
|
E
y
,max
|
.
044018-5
CHUN-JU WU
et al.
PHYS. REV. APPLIED
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[1] H. J. Kimble, The quantum internet,
Nature (London)
453
,
1023 (2008).
[2] S. Wehner, D. Elkouss, and R. Hanson, Quantum internet:
A vision for the road ahead,
Science
362
, 9288 (2018).
[3] D. D. Awschalom, R. Hanson, J. Wrachtrup, and B.
B. Zhou, Quantum technologies with optically interfaced
solid-state spins,
Nat. Photonics
12
, 516 (2018).
[4] G. Wolfowicz, F. J. Heremans, C. P. Anderson, S. Kanai,
H. Seo, A. Gali, G. Galli, and D. D. Awschalom, Quantum
guidelines for solid-state spin defects,
Nat. Rev. Mater.
6
,
906 (2021).
[5] M. Pompili, S. L. N. Hermans, S. Baier, H. K. C. Beuk-
ers, P. C. Humphreys, R. N. Schouten, R. F. L. Vermeulen,
M. J. Tiggelman, L. dos Santos Martins, B. Dirkse, S.
Wehner, and R. Hanson, Realization of a multinode quan-
tum network of remote solid-state qubits,
Science
372
, 259
(2021).
[6] S. L. N. Hermans, M. Pompili, H. K. C. Beukers, S. Baier,
J. Borregaard, and R. Hanson, Qubit teleportation between
non-neighbouring nodes in a quantum network,
Nature
(London)
605
, 663 (2022).
[7] Z.-H. Zhang, P. Stevenson, G. m. H. Thiering, B. C. Rose,
D. Huang, A. M. Edmonds, M. L. Markham, S. A. Lyon,
A. Gali, and N. P. de Leon, Optically detected magnetic
resonance in neutral silicon vacancy centers in diamond via
bound exciton states,
Phys.Rev.Lett.
125
, 237402 (2020).
[8] P.-J. Stas, Y. Q. Huan, B. Machielse, E. N. Knall, A. Suley-
manzade, B. Pingault, M. Sutula, S. W. Ding, C. M. Knaut,
D. R. Assumpcao, Y.-C. Wei, M. K. Bhaskar, R. Riedinger,
D. D. Sukachev, H. Park, M. Lon
ˇ
car, D. S. Levonian, and
M. D. Lukin, Robust multi-qubit quantum network node
with integrated error detection,
Science
378
, 557 (2022).
[9] A. E. Rugar, S. Aghaeimeibodi, D. Riedel, C. Dory, H. Lu,
P. J. McQuade, Z.-X. Shen, N. A. Melosh, and J. Vu
ˇ
ckovi
́
c,
Quantum photonic interface for tin-vacancy centers in dia-
mond,
Phys.Rev.X
11
, 031021 (2021).
[10] R. Debroux, C. P. Michaels, C. M. Purser, N. Wan, M.
E. Trusheim, J. Arjona Martínez, R. A. Parker, A. M.
Stramma,K.C.Chen,L.deSantis,E.M.Alexeev,A.C.
Ferrari, D. Englund, D. A. Gangloff, and M. Atatüre, Quan-
tum control of the tin-vacancy spin qubit in diamond,
Phys.
Rev. X
11
, 041041 (2021).
[11] G. Wolfowicz, C. P. Anderson, B. Diler, O. G. Poluektov, F.
J. Heremans, and D. D. Awschalom, Vanadium spin qubits
as telecom quantum emitters in silicon carbide,
Sci. Adv.
6
,
eaaz1192 (2020).
[12] D. M. Lukin, M. A. Guidry, and J. Vu
ˇ
ckovi
́
c, Integrated
quantum photonics with silicon carbide: Challenges and
prospects,
PRX Quantum
1
, 020102 (2020).
[13] D. B. Higginbottom
et al.
, Optical observation of single
spins in silicon,
Nature (London)
607
, 266 (2022).
[14] J. M. Kindem, A. Ruskuc, J. G. Bartholomew, J. Rochman,
Y. Q. Huan, and A. Faraon, Control and single-shot read-
out of an ion embedded in a nanophotonic cavity,
Nature
(London)
580
, 201 (2020).
[15] S. Chen, M. Raha, C. M. Phenicie, S. Ourari, and J. D.
Thompson, Parallel single-shot measurement and coher-
ent control of solid-state spins below the diffraction limit,
Science
370
, 592 (2020).
[16] P. Stevenson, C. M. Phenicie, I. Gray, S. P. Horvath, S.
Welinski, A. M. Ferrenti, A. Ferrier, P. Goldner, S. Das, R.
Ramesh, R. J. Cava, N. P. de Leon, and J. D. Thompson,
Erbium-implanted materials for quantum communication
applications,
Phys. Rev. B
105
, 224106 (2022).
[17] M. Zhong, M. P. Hedges, R. L. Ahlefeldt, J. G.
Bartholomew, S. E. Beavan, S. M. Wittig, J. J. Longdell,
and M. J. Sellars, Optically addressable nuclear spins in a
solid with a six-hour coherence time,
Nature (London)
517
,
177 (2015).
[18] A. Ruskuc, C.-J. Wu, J. Rochman, J. Choi, and A. Faraon,
Nuclear spin-wave quantum register for a solid-state qubit,
Nature (London)
602
, 408 (2022).
[19] S. Dutta, E. A. Goldschmidt, S. Barik, U. Saha, and
E. Waks, Integrated Photonic Platform for Rare-Earth
Ions in Thin Film Lithium Niobate,
Nano Lett.
20
, 741
(2020).
[20] K. Xia, F. Sardi, C. Sauerzapf, T. Kornher, H.-W. Becker, Z.
Kis, L. Kovacs, D. Dertli, J. Foglszinger, R. Kolesov, and
J. Wrachtrup, Tunable microcavities coupled to rare-earth
quantum emitters,
Optica
9
, 445 (2022).
[21] A. Gritsch, L. Weiss, J. Früh, S. Rinner, and A. Reis-
erer, Narrow optical transitions in erbium-implanted silicon
waveguides,
Phys.Rev.X
12
, 041009 (2022).
[22] A. M. Dibos, M. Raha, C. M. Phenicie, and J. D. Thompson,
Atomic source of single photons in the telecom band,
Phys.
Rev. Lett.
120
, 243601 (2018).
[23] D. Huang, A. Abulnaga, S. Welinski, M. Raha, J. D.
Thompson, and N. P. de Leon, Hybrid III-V diamond pho-
tonic platform for quantum nodes based on neutral silicon
vacancy centers in diamond,
Opt. Express
29
, 9174 (2021).
[24] D. Riedel, I. Söllner, B. J. Shields, S. Starosielec, P. Appel,
E. Neu, P. Maletinsky, and R. J. Warburton, Determin-
istic enhancement of coherent photon generation from a
nitrogen-vacancy center in ultrapure diamond,
Phys. Rev.
X
7
, 031040 (2017).
[25] B. Merkel, A. Ulanowski, and A. Reiserer, Coherent and
purcell-enhanced emission from erbium dopants in a cryo-
genic high-
Q
resonator,
Phys.Rev.X
10
, 041025 (2020).
[26] T. Zhong, J. Rochman, J. M. Kindem, E. Miyazono, and A.
Faraon, High quality factor nanophotonic resonators in bulk
rare-earth doped crystals,
Opt. Express
24
, 536 (2016).
[27] L. Midolo, T. Pregnolato, G. Kiršansk
̇
e, and S. Stobbe,
Soft-mask fabrication of gallium arsenide nanomembranes
for integrated quantum photonics,
Nanotechnology
26
,
484002 (2015).
[28] K. Kuruma, Y. Ota, M. Kakuda, S. Iwamoto, and Y.
Arakawa, Surface-passivated high-
Q
GaAs photonic crys-
tal nanocavity with quantum dots,
APL Photonics
5
,
046106 (2020).
[29] A. Tiranov, V. Angelopoulou, C. J. van Diepen, B. Schrin-
ski, O. A. D. Sandberg, Y. Wang, L. Midolo, S. Scholz,
A. D. Wieck, A. Ludwig, A. S. Sørensen, and P. Lodahl,
Collective super- and subradiant dynamics between distant
optical quantum emitters,
Science
379
, 389 (2023).
[30] T. Komljenovic, D. Huang, P. Pintus, M. A. Tran, M. L.
Davenport, and J. E. Bowers, Photonic Integrated Circuits
Using Heterogeneous Integration on Silicon,
Proc. IEEE
106
, 2246 (2018).
044018-6
NEAR-INFRARED HYBRID QUANTUM PHOTONIC INTERFACE. . .
PHYS. REV. APPLIED
20,
044018 (2023)
[31] Q. Quan and M. Loncar, Deterministic design of wave-
length scale, ultra-high Q photonic crystal nanobeam cavi-
ties,
Opt. Express
19
, 18529 (2011).
[32] E. Miyazono, I. Craiciu, A. Arbabi, T. Zhong, and A.
Faraon, Coupling erbium dopants in yttrium orthosilicate to
silicon photonic resonators and waveguides,
Opt. Express
25
, 2863 (2017).
[33] J. M. Kindem, J. G. Bartholomew, P. J. T. Woodburn, T.
Zhong, I. Craiciu, R. L. Cone, C. W. Thiel, and A. Faraon,
Characterization of
171
Yb
3
+
:YVO
4
for photonic quantum
technologies,
Phys.Rev.B
98
, 024404 (2018).
[34] G. Sallen, A. Tribu, T. Aichele, R. André, L. Besombes,
C. Bougerol, M. Richard, S. Tatarenko, K. Kheng, and
J. P. Poizat, Subnanosecond spectral diffusion measure-
ment using photon correlation,
Nat. Photonics
4
, 696
(2010).
[35] E. M. Purcell, Spontaneous emission probabilities at radio
frequencies,
Phys. Rev.
69
, 681 (1946).
[36] B. Guha, F. Marsault, F. Cadiz, L. Morgenroth, V. Ulin, V.
Berkovitz, A. Lemaître, C. Gomez, A. Amo, S. Combrié,
B. Gérard, G. Leo, and I. Favero, Surface-enhanced gallium
arsenide photonic resonator with quality factor of 6
×
10
6
,
Optica
4
, 218 (2017).
[37] X. Zhou, I. Kulkova, T. Lund-Hansen, S. L. Hansen, P.
Lodahl, and L. Midolo, High-efficiency shallow-etched
grating on GaAs membranes for quantum photonic appli-
cations,
Appl. Phys. Lett.
113
, 251103 (2018).
[38] E. N. Knall, C. M. Knaut, R. Bekenstein, D. R. Assump-
cao, P. L. Stroganov, W. Gong, Y. Q. Huan, P.-J. Stas, B.
Machielse, M. Chalupnik, D. Levonian, A. Suleymanzade,
R. Riedinger, H. Park, M. Lon
ˇ
car, M. K. Bhaskar, and M.
D. Lukin, Efficient source of shaped single photons based
on an integrated diamond nanophotonic system,
Phys. Rev.
Lett.
129
, 053603 (2022).
[39] S. Ourari, Ł. Dusanowski, S. P. Horvath, M. T. Uysal, C. M.
Phenicie, P. Stevenson, M. Raha, S. Chen, R. J. Cava, N. P.
de Leon, and J. D. Thompson, Indistinguishable telecom
band photons from a single erbium ion in the solid state,
arXiv e-prints ,
arXiv:2301.03564
(2023).
[40] I. Friel, S. Clewes, H. Dhillon, N. Perkins, D. Twitchen,
and G. Scarsbrook, Control of surface and bulk crystalline
quality in single crystal diamond grown by chemical vapour
deposition,
Diam. Relat. Mater.
18
, 808 (2009).
[41] S. Sangtawesin, B. L. Dwyer, S. Srinivasan, J. J. Allred,
L. V. H. Rodgers, K. De Greve, A. Stacey, N. Dontschuk,
K. M. O’Donnell, D. Hu, D. A. Evans, C. Jaye, D. A.
Fischer, M. L. Markham, D. J. Twitchen, H. Park, M. D.
Lukin, and N. P. de Leon, Origins of Diamond Surface
Noise Probed by Correlating Single-Spin Measurements
with Surface Spectroscopy,
Phys. Rev. X
9
, 031052 (2019).
044018-7