Searching for Dark Matter with AION (Atom Interferometer Observatory and Network) Sarah Alam Malik Imperial College London Dark matter Evidence from a variety of scales : – galaxy and galaxy clusters – large scale structure forma6on – Cosmic Microwave Background Dark matter Dark energy Nature of dark matter? One of the most fundamental questions in physics 2 Dark Matter : Landscape of candidates Ultra-light Dark Matter WIMPs Primordial black holes 68 10−22 103 109 1012 10 mDM [eV] !3 Dark Matter : Landscape of candidates Ultra-light Dark Matter WIMPs Primordial black holes 68 10−22 103 109 1012 10 mDM [eV] WIMPs very well motivated theoretically, independently from cosmology and particle physics Direct detection and colliders highly constrained large range of parameter space !4 Ultra light Dark Matter (ULDM) An attractive alternative to WIMPs : ULDM covers broad category of theoretical candidates Ultra-light Dark Matter WIMPs Primordial black holes 68 10−22 103 109 1012 10 mDM [eV] Axions - Proposed by Peccei and Quinn (PQ) as an elegant solution to the ‘strong CP problem’ : postulated a new global U(1) symmetry that is spontaneously broken at some large energy scale. - Consequence of this mechanism is a new pseudoscalar boson, the axion, which is the Nambu- Goldstone boson of the PQ symmetry. - This PQ symmetry explicitly broken at low energies, so axion acquires a small mass - Properties of axions closely related to those of neutral pions, two-photon interaction plays a key role for most searches Axion-like particles (ALPs) - String theory predicts existence of axion-like massive scalar fields. !5 Ultra light Dark Matter (ULDM) Experiments searching for these include helioscope searches, Light-Shining-Through-Wall, and haloscope searches Oscillation probability Helioscope Searches Light-Shining-Through-Wall ● Probability is given by ggf coupling Form factor to take into account resonant modes CERN Axion Solar Telescope (CAST) : uses a refurbished LHC test magnet (9T) pointed towards Sun Nov 7, 2018 S Santpur 12 !6 Future projections Ultra light Dark Matter (ULDM) These experiments cover a large range of phase space Nov 7,But, 2018 ULDM candidates with masses in S the Santpur range 10 − 22 – 10 − 14 eV requires new approaches17 !7 Atom Interferometry One of the emerging technologies that shows promise to probe this mass range is quantum sensors in the form of atom interferometer. • Exploit the wave-like behavior of matter. Typical de Broglie wavelength of atom much smaller than optical wavelength, atom interferometers are remarkably sensitive devices • Analogous to laser interferometers by dividing, reflecting and then recombining atomic wavepackets to produce an interference pattern. beam splitter mirror beam splitter 8 Atom Interferometry Current-generation interferometers based on two-photon Raman transitions driven by counter propagating beams beam splitter mirror beam splitter |e> Energy ω2 ω1 |2> |1> Momentum ๏ Atom starts in ground state |1> ๏ A π/2 optical Raman pulse splits atomic wavefunction into an equal superposition of |1⟩ and |2⟩ ๏ Transition driven by counter-propagating light beams with frequencies ω1 and ω2 ; absorption of photon with frequency ω1 and stimulated emission of frequency ω2 ๏ Momentum transfer of to the wave function ℏkeff component in state |1> 9 Atom Interferometry beam splitter mirror beam splitter ๏ Two components propagate freely for a time T ๏ A π pulse swaps the internal states and exchanges momenta 10 Atom Interferometry beam splitter mirror beam splitter ๏ A π/2 pulse closes interferometer sequence ๏ Produce interference fringes in the populations of |1> and |2> ๏ Accumulation of phase along two paths Any efect that modifies the energy across the 2 arms of the interferometer appears in this interferometer phase, this can be used to constrain new physics that couples to matter. 11 Atom Interferometer Observatory Network (AION) A UK-led initiative proposing a series of multi-purpose atom interferometers with progressively increasing baselines to : • Explore well-motivated ultra-light dark matter candidates several orders of magnitude beyond current bounds; • Explore mid-frequency band GWs from the very early Universe and astrophysical sources • Potential sensitivity to searches for new particles and fields such as fifth forces, dark energy, precision measurements of variations in fundamental constants, basic physical principles such as foundations of quantum mechanics and Lorentz invariance. !12 Atom Interferometer Observatory Network (AION) Core team !13 Atom Interferometer Observatory Network (AION) Stage 1 : AION-10 Construct 10m atom interferometer following a similar apparatus at Stanford as prototype 1. Strontium atoms are laser-cooled in a 2D magneto-optical trap (MOT) using the 461nm transition 2. Cooled in a 3D MOT using blue 461nm light and red 689nm light 3. Ultracold atoms are transported to interferometry chamber 4. Atoms are launched upwards 5. Atoms follow a parabolic freefall trajectory, during which interferometry sequence is performed. 14 6. Interference fringes are detected using an imaging system. Atom Interferometer Observatory Network (AION) Stage 2 : AION-100 MAGIS-100 100m atom interferometer is planned that would be sensitive to ULDM - 2 ensembles of atom interferometers along a single vertical baseline. - Signal would be a differential phase shift between the two interferometers. - Potential sensitivity to ULDM in the mass range 10−22 – 10−14 Close collaboration on an international level with the US initiative, MAGIS-100, which pursues a similar goal of an eventual km-scale atom interferometer on a comparable timescale. 15 Ultra light scalar dark matter Ultra-light spin 0 particles are expected to form a coherently oscillating classical field ϕ(t) = ϕ0cos(Eϕt/ℏ) m2ϕ2 Energy density of ρ = 0 2 16 ASIMINA ARVANITAKI et al. PHYS. REV. D 97, 075020 (2018) 1 μ 1 2 2 single atomic species by exploiting the time-domain L μϕ ϕ − m ϕ 1 ¼þ2 ∂ ∂ 2 ϕ ð Þ response of a differential atomic interferometer to a scalar DM wave. The search strategy outlined below has a de μν discovery reach for scalar DM couplings that is potentially − 4πG ϕ d m ee¯ − F F ; 2 N m e e 4 μν ð Þ orders of magnitude better than existing constraints and ASIMINA ARVANITAKI et al. PHYS. REV. D 97, 075020 (2018) pffiffiffiffiffiffiffiffiffiffiffiffi proposals in its frequency band and is complementary to where we parametrized the leading interaction with electrons 1 1 the low-frequency, broadband strategies of Refs. [9,13] and μand photons2 2 relative to gravity as insingle Refs. atomic[17,18] species; G is by exploiting the time-domain L μϕ ϕ − m ϕϕ 1 N the high-frequency, resonant searches of Ref. [12]. ¼þ2 ∂ ∂ Newton2 ’s constant, so d dð Þ 1 wouldresponse be of the a couplings differential atomic interferometer to a scalar m e e DM wave. The search strategyAn outlined electronic below transition has a energy ωA depends on the values ASIMINA ARVANITAKI¼ ¼ et al. PHYS. REV. D 97, 075020 (2018) of a scalar graviton.de μν We employ unitsdiscovery in which reachℏ forc scalar1. DMof couplingsm e and thatα and is potentially so will oscillate itself in the presence of a − 4πGNϕ dm m eee¯ − FμνF ; 2 ¼ ¼ The couplingse 4 in Eq. (2) couldð originateÞ orders from of a magnitude Higgs portal better thanscalar existing DM wave: constraints and Ultra light scalar dark matter pffiffiffiffiffiffiffiffiffiffiffifficoupling of the form bϕ H 2, whichproposals is one in its ultraviolet frequency band and is complementary to L ⊃1 1 PHYSICAL REVIEW D 97, 075020 (2018) single atomic species by exploiting the time-domain where we parametrized the leading interaction with electronsj j μ 2 2 ASIMINA ARVANITAKIcompletion intoet a al.L renormalizableμϕ modelϕ −the low-frequency, withm ϕϕ a particularly broadband strategies1 of Refs.PHYS.[9,13] and REV. D 97, 075020 (2018) and photons relative to gravity as in Refs. [17,18]¼þ2; G is 2 ð Þω tresponseω ofω a differentialcos m t ; atomic interferometer6 to a scalar low cutoff [7]. Scalar fields∂ N with∂ quadraticthe high-frequency, couplings resonant to searches of Ref.A [12]≃. A Δ A ϕ ’ ð Þ þ ð Þ ð Þ Newton s constant, so dm e de 1 would be the couplings An electronic transition energy ω depends onDM the values wave. The search strategy outlined below has a matter¼ [19¼–21], e.g. L ⊃ ϕ2 H 2, give rise to analogous A of a scalar graviton.1 We employ units1 in which ℏ c 1. of m and α andde sosingle will oscillateμν atomic itself in species the presencediscovery by of exploiting a reach for the scalar time-domain DM couplings that is potentially L ϕ μϕ m 2 ϕ2 − ¼ 4¼πj Gj ϕ d em ee¯ 1− F F ; 2 The couplings in Eq. (2)signaturesμcould originate− as the fromϕ linear a Higgs couplings portalN butscalar havem e DM drasticallye wave: moreμν ¼þ2 ∂ ∂ 2 ð Þ 4 response of a differentialð Þ ΔωAorders atomicωA of4π magnitude interferometerGNϕ0 dm betterξd toe : athan scalar existing7 constraints and coupling of the form fine-tunedL ⊃ bϕ H 2 masses, which is for one the ultraviolet same physical effect, so we shall ≡ ð e þ Þ ð Þ j j pffiffiffiffiffiffiffiffiffiffiffiffi DM wave. The searchproposals strategy in outlined its frequency below band has and a is complementary to completion into a renormalizablenot consider model them with further. a particularly pffiffiffiffiffiffiffiffiffiffiffiffi Scalar fieldwhere we parametrizedde μν theElectron leadingω interactionA t ≃PhotondiscoveryωA withΔ ωA cos electrons reachm ϕt for; scalarthe DM low-frequency,6 couplings that broadband is potentially strategies of Refs. [9,13] and low cutoff [7]. Scalar− 4 fieldsπBosonicGNϕ withd DMm quadraticm mucheee¯ − couplings lighterFμν thanF to 1 eV; is a highly2 ð classicalÞ þ Above,ð Þ we have neglectedð Þ the vvir-suppressed spatial 2 2ande photons relative to gravitycoupling as incoupling Refs. [17,18]; G is matter [19–21], e.g.