Beam drawn red; real 795 nm light is invisible.
CablesBNC signalSMA RFtrigger / gatepowercoilheater
Detector · scope
Objectives
Below: identified equipment, probable bill of materials and the cost estimate (scroll the page, the mouse wheel zooms the 3D view)
Quantum Spain-style bench: what the photograph shows
This bench is reconstructed from a single photograph of a Quantum Spain-style EIT bench, not from drawings. Positions are approximate, part names marked “look” or “class” are look-alikes, and anything not visible is marked “assumed”. The optical chain is this guide’s own Zeeman-EIT chain (same physics as the 3D Bench tab) re-laid on the two boards; in the simulator the lock, the EIT window and the pulse storage all work.
Reading of the bench
- Left breadboard: laser input and SAS lock. Fibre-coupled laser light (blue PM patch cables with green FC/APC connectors), isolator, steering mirrors, a pick-off, and the saturated-absorption arm with the white 3D-printed reference-cell module (banana jacks and a small board on top).
- Right breadboard (Thorlabs MB4545/M): the EIT board. Two red-housed AOMs with gold SMA inputs, many waveplates, cubes and lenses, the white EIT-cell module with red heater and coil leads, and a black detector or camera housing at the right edge.
- Shelf behind the boards: two Thorlabs benchtop controllers, two Rigol generators, two TENMA DC supplies labelled HEATER and COILS, and a Rigol DS1102 oscilloscope at each end of the boards.
Assumption about the lock. The two double-pass AOMs shift the beams by +160 MHz, and the SAS arm has no AOM. The simulator treats the lock point as the atomic resonance, which hides that offset. A real bench needs the lock moved by about 160 MHz (for example with an AOM in the SAS arm), and the photograph does not show how this is done.
The EIT cell label: TRT-Rb/Ne-10T-20x75 (Triad Technology Inc.)
The videos of this bench show the label TRT-Rb/Ne-10T-20x75 on the EIT cell, and the maker is Triad Technology Inc. (given by the owner of this guide). The name “TRT-…” is not in Triad’s standard catalogue, which lists cells as TT-RB-75-V-x (natural Rb), TT-RB85-… and TT-RB87-…, in two sizes only: Ø25 × 75 mm Pyrex and Ø19 × 75 mm quartz. Triad says neon and other buffer gases and custom cells are available on request. So the reading below is an interpretation from that naming, not a specification.
| Part of the label | Reading | Status |
|---|---|---|
| TRT | a Triad series or order code for a custom cell; not defined in the public catalogue or in the Sacher brochure of Triad cells | unknown |
| Rb | rubidium. In Triad’s naming plain “RB” is natural rubidium (72 % 85Rb, 28 % 87Rb); isotope cells are written RB85 or RB87 | likely natural |
| Ne | neon buffer gas | clear |
| 10T | 10 Torr of neon (the same fill as the cell of the published Zeeman-EIT set-up that our guide follows) | likely |
| 20x75 | 20 mm diameter × 75 mm length (assumed order). Ø20 is not a Triad standard size (their standard cells are Ø25 or Ø19), so probably a custom size | likely |
What it would mean (calculated for this guide, see the Q&A on this label):
- Long cell. A 75 mm path has three times the optical depth of our 25 mm path at the same temperature. For an optical depth of about 10 on the 87Rb line a natural-Rb cell needs about 62 °C (about 47 °C if it were enriched). The 1.2 W DC heater seen on the shelf (about 2.4 V and 0.5 A) would hold such a cell near 45 to 50 °C, where a natural cell has an optical depth of only about 2 to 4: enough for clear EIT, with less contrast. This is a guess.
- Natural rubidium works for this line. The nearest 85Rb line is about 1.7 GHz from the 87Rb F = 2 → F′ = 1 line, so 85Rb takes only about 5 to 20 % of the probe (optical depth 0.05 to 0.2) at 45 to 62 °C. The price is the lower 87Rb density (28 %), which the long path makes up for.
- Neon at 10 Torr broadens the D1 line by about 100 MHz, shifts it by about −11 MHz, and slows the diffusion of the atoms so that their coherence lasts much longer than the time they take to cross the beam.
- A 75 mm cell needs a long, uniform magnetic field. The coil of our guide (42 turns, 140 mm) would give a field spread of 2.4 % over 75 mm instead of 0.2 % over 25 mm. How well the Spain-style coil does is not known; a broader line is likely.
Instruments identified
| Tag / label | Item | What is readable | Confidence |
|---|---|---|---|
| LDC | Thorlabs benchtop laser diode current controller (LDC200C-series look) | Thorlabs logo; display 146.88, taken as laser current in mA (close to the 160 mA of a 795 nm DFB at 15 mW) | brand high, model low |
| TED | Thorlabs benchtop TEC controller (TED200C-series look) | Thorlabs logo; display 9.021, probably the thermistor reading in kΩ | brand high, model low |
| FG | Rigol function / arbitrary generator, small, colour screen, 3 BNC outputs (DG800 look) | Rigol logo | brand high, model low |
| (none) | Rigol two-channel arbitrary generator, larger, split screen (DG4000 look) | Rigol logo; two yellow and two blue BNC outputs. Likely the two-channel source for the AOMs | brand high, model low |
| HEATER | TENMA linear DC power supply | Label HEATER; display about 02.40 and 0.500 (V and A, my reading) | high |
| COILS | TENMA linear DC power supply | Label COILS; display about 01.00 and 0.080 (about 80 mA through the solenoid, my reading) | high |
| DSO1, DSO2 | Rigol DS1102 digital oscilloscopes (two): 100 MHz, 2 analogue channels, up to 1 GSa/s (the suffix E or Z-E is not stated) | Rigol logo, colour screens; the model DS1102 is taken from the YouTube videos | high (model from the videos) |
| (none) | PC keyboard and monitor behind the shelf, power strips under it | Visible | high |
Optics and mechanics: probable bill of materials (no prices)
| Item | Likely class | Seen / est. qty | Board | Confidence |
|---|---|---|---|---|
| Breadboards | Thorlabs MB4545/M, 450 × 450 mm, M6 on 25 mm pitch, black anodised | 2 (label “MB4545/M” readable) | both | high |
| Acousto-optic modulators | Red-housed modules, gold SMA input, white label (maker unreadable; possibly Thorlabs) | 2 | 2 | medium |
| Rubidium vapour cell modules | White 3D-printed housings with heater and coil leads (a shield may be inside). The EIT cell is labelled TRT-Rb/Ne-10T-20x75 in the YouTube videos (maker Triad Technology Inc.): Rb (natural, by Triad’s naming) with neon buffer gas at 10 Torr, 20 × 75 mm (see “The EIT cell label” below) | 2: reference cell (left), EIT cell (right) | 1, 2 | high (label read from the videos; maker given by the owner) |
| Kinematic mirror mounts | Black two-axis mounts with asset labels (Thorlabs KM100 / Polaris class) | about 20–25 | both | count rough |
| Polarizing beamsplitter cubes | Clear cubes on kinematic cube mounts with white tags | about 6–8 | both | count rough |
| Waveplates in rotation mounts | Black rotation mounts with white angle scale (RSP1 type) | about 6–8 | both | count rough |
| Lenses and tubes | Lens mounts and SM-thread tubes, some with blue AR tint | about 8–10 | both | count rough |
| Posts, post holders, clamping forks | Silver posts; grey and red slotted forks (CF125 type) | one set per optic, about 50 | both | medium |
| Detectors | Black housings with a round aperture (amplified photodetector or camera) | 2 | 1, 2 | low |
| Fibre parts | Blue PM patch cables with green FC/APC connectors, collimators in kinematic mounts, white 900 µm fibre loops | 2–3 cables, ≥ 2 collimators | 1 (to 2) | medium |
| Isolator or collimator tube | Tall cylindrical part at the back of the left board | 1 | 1 | low |
| Cell electronics | Small board with banana jacks on top of the left cell module | 1 | 1 | medium |
| Beam dumps, filters, irises | Not visible in the photo | assumed | both | assumed |
| RF amplifiers and attenuators for the AOMs | Not visible; needed to drive two AOMs from a Rigol generator | assumed hidden | — | assumed |
| Laser-lock electronics | Not visible; added in the simulator so the lock closes | assumed | — | assumed |
What this bench can do
- Laser lock to the Rb D1 line. The SAS arm and the reference cell on board 1, with the Thorlabs current and TEC controllers (about 147 mA is a normal 795 nm DFB drive current) and a Rigol generator for the dither, read on a scope.
- Continuous-wave Zeeman EIT. Control and probe from two AOM arms, opposite circular polarizations, an EIT cell with a heater (about 1.2 W DC) and a solenoid (about 80 mA); linewidth versus control intensity, magnetic field and temperature.
- Slow light and light storage. The two-channel Rigol generator can drive the probe pulse and switch the control AOM off and on, with the second scope on the probe and the trigger.
- Field sensing. The Zeeman EIT line moves 1.4 kHz per milligauss, so the bench can double as a magnetometer.
- Parts the guide’s list does not have: the cat’s-eye lenses in the two AOM arms need a focal length of about 75 mm (80 mm after the AOM, 70 mm to the retro mirror); the control beam expander is f = 30 mm plus f = 100 mm, 130 mm apart.
- Not possible with what is visible: hyperfine (6.8 GHz) EIT (no microwave source or EOM), single-photon-level detection (no photon counters), and absolute efficiency measurements (no calibrated detection).
Cost estimate of this bench (units are public, prices need the group password)
Every unit in the Quantum Spain-style version (the 63 parts drawn above) is priced with the same unit prices as this guide’s costed bill of materials. Left out on purpose: the laser mount, the laser current and TEC controllers, and the breadboard. Group A is what the photo and the simulator show; group B is what is needed to run the bench but is not visible in the photo.
The prices stay on the server until the password is entered; nothing is stored in this page.
| # | Unit | Qty | Unit price (RM) | Line (RM) |
|---|---|---|---|---|
| A · Units in the Quantum Spain-style version | ||||
| 1 | Fibre-coupled 795 nm DFB laser | 1 | — | — |
| 2 | Fibre isolator with FC/APC collimator | 1 | — | — |
| 3 | Mirrors with kinematic mounts | 9 | — | — |
| 4 | Polarizing beamsplitter cubes, uncaged (seen in the videos) | 7 | — | — |
| 5 | Non-polarizing 50:50 cube | 1 | — | — |
| 6 | Half-wave plates with rotation mounts | 4 | — | — |
| 7 | Quarter-wave plates with rotation mounts | 4 | — | — |
| 8 | Lenses with mounts | 5 | — | — |
| 9 | Irises | 3 | — | — |
| 10 | ND filters with holders | 2 | — | — |
| 11 | Beam dumps | 10 | — | — |
| 12 | Glan-Taylor polarizer with rotation mount | 1 | — | — |
| 13 | Acousto-optic modulators | 2 | — | — |
| 14 | AOM tilt stages (2) and cell holder (1) | 3 | — | — |
| 15 | SAS reference cell with holder | 1 | — | — |
| 16 | EIT vapour cell with two foil heaters | 1 | — | — |
| 17 | Photodiodes (SAS and detector) | 2 | — | — |
| 18 | Photodiode power supply | 1 | — | — |
| 19 | Posts, post holders and clamping forks (one set per optic) | 39 | — | — |
| 20 | Laser-lock electronics (assumed, not visible) | 1 | — | — |
| 21 | Function generator | 1 | — | — |
| 22 | Two-channel RF source | 1 | — | — |
| 23 | DC supplies for the heater and the coil | 2 | — | — |
| 24 | Oscilloscopes | 2 | — | — |
| Visible in the version | — | |||
| B · Needed to run it, not visible in the photo (assumed) | ||||
| 25 | RF power amplifiers | 2 | — | — |
| 26 | RF switches | 2 | — | — |
| 27 | RF step attenuators | 2 | — | — |
| 28 | DC supply for the RF parts | 1 | — | — |
| 29 | Cables: BNC (12), SMA (8), adapters, leads | 1 | — | — |
| 30 | Solenoid former and wire | 1 | — | — |
| 31 | µ-metal shield, 3 layers (only if not inside the white boxes) | 1 | — | — |
| 32 | Degaussing coil with variac | 1 | — | — |
| 33 | Enclosure panels and beam tubes | 1 | — | — |
| Needed but not visible | — | |||
| Total A + B | — | |||
| Our BOM for comparison (same exclusions, optional items left out) | — | |||
Why it differs from our bill of materials
- Fewer mounts: 39 post sets and 9 mirrors in the Spain-style version, against 60 post sets and 11 mirrors in ours.
- The cell is heated from a plain DC supply instead of a temperature controller.
- No optical power meter, no multimeter, no fluxgate magnetometer and no laser-safety items.
Caveats
- The real photo shows more mounts than the simulated layout (about 20–25 mirrors against 9); each extra mirror with its mount and post adds one more line of cost.
- The laser is priced as this guide’s DFB (the laser in the photo is not visible), and the two-channel Rigol source is priced as this guide’s two-channel RF synthesiser.
- The two Rigol DS1102 oscilloscopes are priced as this guide’s oscilloscope line (E02); the EIT cell is priced as this guide’s cell (C01) because the price of the Triad cell is not known.
- Prices are the guide’s planning prices, not quotations.
Reconstructed by this guide from one photograph; this is an illustration of that style of bench, not a drawing of any specific laboratory.