⚛️ Tool 01 · Atom Library

🧪 Laser-Coolable Atoms

Spectroscopic data for 15 atoms · canonical data sheets · US research groups in neutral-atom quantum science. A starting-point reference for anyone entering the field of ultracold atoms.

This page is a starting-point resource for anyone entering the field of ultracold atoms and neutral-atom quantum science. Choose an atom family below to explore key spectroscopic properties, download canonical data sheets (Steck and others), and find the leading US research groups working with each species. A quick comparison table lets you see all atoms side-by-side.

📊 Quick Comparison

Filter:
Atom Z A Statistics Family Cool. λ (nm) Γ/2π (MHz) T_D (μK) T_r (μK) Nuclear spin I HF split (GHz) Key notes
⁶Li 36 Fermion Alkali 671.05.871413.54 10.228 Strong Feshbach res.; Li-Cs molecules
⁷Li 37 Boson Alkali 671.05.871413.54 3/20.804 Early BEC; light mass → large recoil
²³Na 1123 Boson Alkali 589.09.802352.40 3/21.772 First BEC (Ketterle 1995, Nobel 2001)
³⁹K 1939 Boson Alkali 767.06.041450.42 3/20.462 Feshbach res.; Fermi-Hubbard model
⁴⁰K 1940 Fermion Alkali 767.06.041450.42 4— Fermionic isotope; degenerate Fermi gas
⁴¹K 1941 Boson Alkali 767.06.041450.42 3/20.254 Less common; BEC demonstrated
⁸⁵Rb 3785 Boson Alkali 780.26.071460.36 5/23.036 Feshbach res. for tuneable interactions
⁸⁷Rb 3787 Boson Alkali 780.26.071460.36 3/26.835 Most popular qubit (6.8 GHz clock)
¹³³Cs 55133 Boson Alkali 852.35.231250.20 7/29.193 Defines the SI second; Li-Cs molecules
⁸⁸Sr 3888 Boson Alkaline Earth 461.032.07700.46 0— Narrow 689 nm line → T_D = 0.18 μK; optical clock
⁸⁷Sr 3887 Fermion Alkaline Earth 461.032.07700.46 9/2— 10 nuclear spin states; SU(N) physics
¹⁷⁴Yb 70174 Boson Alkaline Earth 399.028.04.40.20 0— 556 nm narrow line; mHz clock transition
¹⁷¹Yb 70171 Fermion Alkaline Earth 399.028.04.40.20 1/2— Effective spin-1/2 qubit; clock QC
¹⁶⁴Dy 66164 Boson Magnetic 421.0——— 0— Largest magnetic moment (10 μ_B); dipolar physics
¹⁶⁸Er 68168 Boson Magnetic 401.0——— 0— Large magnetic moment (7 μ_B); anisotropic interactions

T_D = Doppler temperature limit  |  T_r = single-photon recoil temperature  |  HF = ground-state hyperfine splitting  |  — = not applicable or varies by isotope. Broad-line values shown for alkaline-earth atoms; narrow intercombination lines give much lower T_D.

📈 Visual Comparison

Doppler Temperature T_D (μK) — broad cooling line
Natural Linewidth Γ/2π (MHz) — broad cooling line
Alkali Alkaline Earth
Note on alkaline-earth narrow lines: Sr-88 and Sr-87 have a narrow 689 nm intercombination line with Γ/2π = 7.6 kHz, giving a Doppler limit of T_D = 0.18 μK — far below the broad-line value shown above. Yb has a 556 nm line with Γ/2π = 182 kHz. These narrow lines enable sub-Doppler temperatures without requiring sub-Doppler stages (polarization-gradient cooling etc.).

🔬 Atom Details

Alkali atoms (Li, Na, K, Rb, Cs) have a single valence electron, giving a simple hydrogen-like level structure. Their D1 and D2 lines in the visible/near-IR are accessible with diode lasers. Hyperfine ground states form natural two-level qubits. Rb-87 (6.8 GHz clock) and Cs-133 (9.2 GHz, defines the SI second) are the two most widely used qubit atoms today.
Why it's used

Lightest alkali. Large recoil energy enables efficient sub-Doppler cooling. Strong Feshbach resonances allow tunable interactions. Li-6 is the primary fermionic atom for strongly-correlated physics and BEC-BCS crossover experiments. Used in Li-Cs molecular assembly (Hood Lab, Purdue).

Key spectral lines
D1: 670.992 nm | D2: 670.977 nm | Γ/2π = 5.87 MHz
Qubit transition

⁷Li: |F=1⟩ ↔ |F=2⟩ hyperfine qubit (803 MHz). ⁶Li: fermionic spin states used for many-body qubits.

Data sheets
📄 ⁶Li properties — Gehm (NCSU) 📚 Steck alkali data index 🔗 NIST Atomic Spectra Database
Further reading

Gehm (2003) — Properties of ⁶Li [NCSU tech doc]

Why it's used

First atom used to achieve BEC (Ketterle group, MIT, 1995 — Nobel Prize 2001). Yellow D-line at 589 nm. Larger scattering length suitable for BEC studies. Being revisited for molecule formation: NaLi, NaK, NaRb, NaCs.

Key spectral lines
D1: 589.756 nm | D2: 588.995 nm | Γ/2π = 9.80 MHz
Qubit transition

|F=1⟩ ↔ |F=2⟩ hyperfine qubit (1772 MHz)

Data sheets
📄 Na-23 — Steck data sheet 📚 Steck alkali data index 🔗 NIST Atomic Spectra Database
Note

The Steck data sheet above is the canonical reference. Steck (2019, updated continuously).

Why it's used

K-40 is the only naturally abundant fermionic alkali; the standard atom for Fermi-Hubbard model simulations in optical lattices. K-39 has accessible Feshbach resonances for tuning interactions. All isotopes share the same 767/770 nm D-lines — diode laser accessible.

Key spectral lines
D1: 770.108 nm | D2: 766.701 nm | Γ/2π = 6.04 MHz
Qubit transition

K-39: |1,−1⟩ ↔ |2,2⟩ clock-like transition

Why it's used

Rb-87 is the most widely used quantum computing atom — large 6.835 GHz hyperfine splitting, convenient 780 nm lasers, and well-understood collisional properties. The backbone of most Rydberg tweezer quantum computers today (Atom Computing, QuEra, Pasqal all use Rb or Sr). Rb-85 has a Feshbach resonance for tunable interaction experiments.

Key spectral lines
D1: 794.979 nm | D2: 780.241 nm | Γ/2π = 6.07 MHz
Qubit transition

Rb-87: |0,0⟩ ↔ |1,1⟩ or |1,−1⟩ ↔ |2,1⟩ "clock" qubit (6835 MHz)

Why it's used

Largest hyperfine splitting of the alkalis (9.193 GHz — defines the SI second). Excellent for optical tweezer work: heavy mass → low recoil → tighter confinement. Used in Li-Cs molecular assembly experiments (Hood Lab, Purdue). The 852 nm D2 line sits in a convenient region for diode lasers (DFB, ECDL).

Key spectral lines
D1: 894.593 nm | D2: 852.347 nm | Γ/2π = 5.23 MHz
Qubit transition

|3,0⟩ ↔ |4,0⟩ "clock" transition (9193 MHz, field-insensitive at zero B-field)

Alkaline-earth and alkaline-earth-like atoms (Ca, Sr, Yb) have two valence electrons, giving rich level structures including ultra-narrow intercombination and clock transitions. These enable sub-recoil cooling on the narrow line, exceptional coherence times, and optical-lattice clocks accurate to 1 part in 10¹⁸. Fermionic isotopes (Sr-87, Yb-171) offer nuclear spin qubits decoupled from the electronic state — ideal for optical-clock quantum computing.
Why it's used

Sr has two laser-cooling stages: the broad 461 nm blue line (Doppler limit 770 μK) and the 689 nm red intercombination line (Γ/2π = 7.6 kHz, T_D = 0.18 μK). The 698 nm clock transition has a linewidth of ~1 mHz. Sr-87 (I = 9/2) gives 10 nuclear spin states for SU(N) physics and quantum simulation. Used in world-leading optical lattice clocks (Ye Lab, JILA).

Key spectral lines
Broad: 461 nm (Γ/2π = 32 MHz, T_D = 770 μK) Narrow: 689 nm (Γ/2π = 7.6 kHz, T_D = 0.18 μK) Clock: 698 nm (~1 mHz linewidth)
Qubit transition

Sr-87 nuclear spin qubit: |m_I = −9/2⟩ ↔ |m_I = −7/2⟩ via the 698 nm clock transition

Why it's used

Yb combines broad (399 nm, Γ/2π = 28 MHz) and narrow (556 nm, Γ/2π = 182 kHz) cooling lines with a mHz-linewidth clock transition at 578 nm. Yb-171 (I = 1/2) is effectively a perfect two-level nuclear-spin qubit. Magic wavelengths at 759 nm make optical lattice clocks insensitive to light shifts.

Key spectral lines
Broad: 399 nm (Γ/2π = 28 MHz) Narrow: 556 nm (Γ/2π = 182 kHz) Clock: 578 nm (mHz linewidth)
Qubit transition

Yb-171: |m_I = +1/2⟩ ↔ |m_I = −1/2⟩ nuclear spin qubit (zero-field insensitive)

Highly magnetic atoms (Cr, Dy, Er) have large magnetic moments (6–10 μ_B), making their inter-particle interactions strongly anisotropic and long-range. This opens the door to dipolar quantum simulation — phenomena impossible with contact- interaction BECs. Dy has the largest magnetic moment of any element (10 μ_B).
Why it's used

Dy-164 has the largest magnetic moment of any element (10 μ_B), enabling strong dipolar interactions and anisotropic collisional physics. Used for dipolar BEC, quantum droplets, and supersolid phases. Cooled on a broad 421 nm line; also has intercombination lines at 598 nm and 626 nm.

Key spectral lines
Main: 421 nm (broad) Narrow: 598 nm, 626 nm (intercombination lines)
Why it's used

Er-168 has a magnetic moment of 7 μ_B and a rich level structure. Dipolar BEC demonstrated by Ferrier-Barbut/Pfau group (Stuttgart) and Grimm group (Innsbruck). Anisotropic scattering leads to distinctive many-body phases. Being explored for dipolar quantum droplets alongside Dy.

Key spectral lines
Main: 401 nm Narrow: 583 nm (intercombination line)

🏛️ US Research Groups in Neutral-Atom Quantum Science

The following groups work on neutral-atom experiments — quantum computing, quantum simulation, precision measurement, and ultracold chemistry — organized by their primary atom(s). Click any group name to visit the lab website.
⁸⁷Rb — Quantum Computing & Simulation (6 groups)
🔗 Lukin Lab
Harvard
Rydberg tweezer quantum processor; many-body physics
🔗 Greiner Lab
Harvard
Quantum simulation, Hubbard model, quantum gas microscope
🔗 Saffman Lab
Wisconsin
Rydberg two-qubit gates, trapped-atom qubits
🔗 Kaufman Lab
Colorado / JILA
Tweezer arrays, quantum optics with atoms
🔗 Bernien Lab
UChicago
Programmable quantum matter, Rydberg arrays
🔗 Weiss Lab
Penn State
Neutral atom qubits, quantum computing
¹³³Cs — Quantum Computing & Molecules (2 groups)
🔗 Chin Lab
UChicago
Strongly correlated gases, Efimov physics, BEC
🔗 Hood Lab
Purdue ★
Li-Cs molecule assembly, optical tweezers, single-atom control
⁶Li / ⁷Li — Fermi Gases & Molecules (4 groups)
🔗 Hulet Lab
Rice
Li-6 Fermi gases, BEC-BCS crossover, solitons
🔗 Zwierlein Lab
MIT
Degenerate Fermi gases, fermionic superfluidity
🔗 DeMarco Lab
UIUC
Fermi-Hubbard model, disordered lattices
🔗 Hood Lab
Purdue ★
Li-Cs molecules in tweezers
²³Na & ¹⁹K — Molecules & BEC (3 groups)
🔗 Ketterle Lab
MIT
First BEC (Nobel 2001); spinor BECs; NaLi molecules
🔗 Zwierlein Lab
MIT
NaLi and NaK ultracold molecules; Fermi gases
🔗 Ni Lab
Harvard
Ultracold polar molecules (NaCs, KRb)
⁸⁸Sr / ⁸⁷Sr — Optical Clocks & Simulation (5 groups)
🔗 Ye Lab
JILA / Colorado
World-leading optical lattice clock; Sr tweezer arrays; quantum simulation
🔗 Killian Lab
Rice
Sr BEC and tweezer arrays, Rydberg excitation
🔗 Thompson Lab
Princeton
Sr cavity QED, quantum networking
🔗 Covey Lab
UIUC
Tweezer arrays with alkaline-earth atoms
🔗 Rey Lab (theory)
JILA / Colorado
AMO theory for Sr, Yb quantum simulation
¹⁷⁴Yb / ¹⁷¹Yb — Clocks & Quantum Computing (4 groups)
🔗 Ye Lab
JILA / Colorado
Yb optical lattice clock; quantum simulation with Yb
🔗 Kaufman Lab
Colorado / JILA
Yb tweezer arrays; quantum optics
🔗 Spielman Lab
NIST / Maryland
Optical lattices, synthetic gauge fields
🔗 Thompson Lab
Princeton
Yb cavity QED
¹⁶⁴Dy / ¹⁶⁸Er — Dipolar Physics (1 group)
🔗 Lev Lab
Stanford
Dy and Er dipolar gases, quantum magnetism

📚 Essential Resources & Tools

📄 Data Sheets
Alkali Data Sheets
📄Li-6 properties — Gehm (NCSU) 📄Na-23 — Steck 📄K properties — Tiecke 📄Rb-85 — Steck 📄Rb-87 — Steck 📄Cs-133 — Steck 📚All Steck sheets →
🔧 Databases & Tools
Spectroscopy Databases
🔗NIST Atomic Spectra Database 🔗NIST Physical Reference Data
Python Libraries
📦ARC — Alkali Rydberg Calculator 📦QuTiP — Open quantum systems 📦pylcp — Laser cooling physics
arXiv searches
🔍quant-ph: neutral atom qubits 🔍cond-mat.quant-gas (recent)
📖 Textbooks & Reviews
Textbooks
Metcalf & van der Straten — Laser Cooling and Trapping (1999) Foot — Atomic Physics (2005) Pethick & Smith — BEC in Dilute Gases (2008)
Review Articles
📄Saffman — Rydberg atom QC (RMP 2010) 📄Kaufman & Ni — Tweezer arrays (Nat. Phys. 2021) 📄Ludlow et al. — Optical clocks (RMP 2015) 📄Chomaz et al. — Dipolar physics (RMP 2023) 📄Browaeys & Lahaye — Rydberg physics (Nat. Phys. 2020)

Data compiled from Steck data sheets, NIST ASD, and primary literature · All links open in a new tab